Tuesday, November 17, 2015

Windows 7 Media Center's alternative to Cable TV is gone forever in Windows 10

Windows 7 Media Center's TV program recording capability is a well kept secret:

It is an unfortunate fact that many individuals with low incomes, as well as a very large number of retired folks on limited budgets, are locked into expensive cable TV subscriptions. Sadly, ever since the introduction of terrestrial (over-the-air) digital television in the USA in 2009, all the old workhorse VCRs have ended up in scrapyards and there are few options left for watching and recording live local commercial TV OTA (Over The Air) programming without a monthly cable service. However, many people are blissfully unaware that they already have the ability to legally watch and record free over-the-air local channels of commercial TV. Why? because many of these people already own a Windows 7 PC or laptop, and most versions of Microsoft Windows 7 already have the necessary Windows Media Center software integrated into Windows 7's Home Premium, Ulltimate, Professional and Enterprise editions - only Windows 7 Home Basic leaves this feature out.
For many people this can be a subscription-free alternative to Cable TV, DVRs and TIVO. If you already own a Windows 7 PC with sufficient hard drive space and are willing to add a PCI-E Tuner card or USB tuner stick, then you can easily enable Window 7's Media Center feature to watch, time-delay and record hundreds of free programs being broadcast over dozens of local and network digital TV broadcast channels and sub-channels that can be accessed by hooking up to a simple indoors or outdoors UHF antenna in most urban areas of the US.

But, be aware that when you push the "Upgrade" button to run the automatic "Free Windows 10 Upgrade" that Windows 7 Media Center will be gone from your PC forever!
You may have noticed the little Windows icon that has been appearing in the bottom right hand corner of your Windows 7 Taskbar. Before you click on it to take advantage of Microsoft's free offer to upgrade from Windows 7 to Windows 10 you should be aware that all the great features of Windows 7's Media Center have been completely eliminated from the newer versions of the Windows 8 and Windows 10 operating systems. More importantly, it will be completely gone forever once you upgrade to Windows 10!
So hold on to, or purchase a new copy of Windows 7 if you wish to take keep this valuable feature. Microsoft has stated that it will continue to support the Widows 7 OS, so it should be widely available for a long time as a flexible, well designed and free alternative to costly cable.

Happauge USB TV Tuner

Here are some basic requirements for watching and recording live over-the-air TV using Windows 7 Media Center:

I recommend starting out with an uncluttered 32-bit or 64-bit PC or laptop with a version of Microsoft Windows 7 with Media Center software that can be dedicated to Media Center use. Because recording a lot of high definition TV can rapidly gobble up your drive space, so you will need at least 512 Gigabytes of available hard drive space for recording TV programs.
For the most satisfying TV watching results you can add a large screen digital TV or monitor with auxiliary VGA, DVI or HDMI inputs. These attach to the corresponding outputs of your PC or laptop. Note that the HDMI connector integrates sound with video, otherwise you will also need additional cables for sound hookup.
A basic ISP (Internet Service Provider) in order to permit Media Center to download its free nightly program guide updates.
Most importantly you will need a TV tuner card that can plug into a spare PCI-E slot in your computer. If you have a laptop, or if you don't want to mess around with the insides of your PC, then you can use a USB tuner stick - one end plugs into a spare rear USB socket on your PC, the other end has a standard 75 ohm antenna "F" connector. Note: Most PCI-E tuner cards and USB tuner sticks are detected automatically after Windows Media Center is enabled. Before you buy, make sure the tuner you select supports ATSC Digital TV. Local Over-The-Air (OTA) HDTV broadcasts available in your area can have the same or better picture quality as the QAM HDTV sent over cable
Depending on your location, you will need an inexpensive indoor or outdoor UHF antenna
For best results I use a Dual TV Tuner PCI Card and a Windows Compatible Remote Control. These allow me to simultaneously watch one program while recording another free over-the air television channel on my large screen TV from the comfort of my sofa.

Still interested? Then why not cut off that cable service?

If you can do without the 1000's of channels you don't need, then why pay for a monthly cable TV subscription when there is so much free high definition and standard digital programming already being broadcast locally OTA (Over The Air) and over the internet? If you are a newcomer to this subject there is some learning involved. Here are some of the possibilities and a guide to get you started:

1. Watch and Record Live over the Air TV:

Windows Media Center has a digital video recorder and media player developed by Microsoft that allows users to view and record live television, as well as organize and play music and videos. It was originally included in various versions of Windows XP Media Center Edition, Windows Vista Home Premium and Ultimate, and all editions of Windows 7 except for Starter and Home Basic.
In April 2012, Microsoft announced that Media Center would not be included in Windows 8, instead, it will be part of a Media Center Pack add-on available only for Windows 8 Pro, and a Pro Pack that upgrades the standard edition of Windows 8 to Windows 8 Pro with Media Center.
DTV Antenna: Depending on your location, many channels can often be picked up with an ordinary rabbit-ears indoor antenna, or you can build a simple yet effective antenna yourself. This ConsumerReports Blog shows you how. In my case, I reused an existing rooftop mounted UHF antenna from the old analog TV days. I tested it first with an old TV attached to a $49 digital converter box and was able to pick up 39 local digital TV channels. If you would rather buy a new one, I found this antenna at a good price. Depending on reception in your area it can be installed indoors, outdoors or in the attic.

Reception: To find out which digital TV broadcast television signals are available in your area, complete with detailed orientation information, use the great online tool at TV Fool. It allows you to "compute the expected signal strength for every channel "in the air" at your location, including adjustments for transmitter power, terrain obstructions, curvature of the Earth, and other factors that affect signal availability".

VCR Replacement: I didn't want to pay a subscription for a DVR or a TIVO box. By using Media Center's Guide and Record TV features, I now have a replacement for my old VCR and can record all my favorite shows using the built-in two-week TV guide which updates daily automatically over the internet .
720P / 1080i TV or Monitor: I already owned a two-year old flat panel Philips TV that had several external inputs that I could hook up to my PC's graphics output. Newer TVs can support VGA, DVI and HDMI digital connectors. Recently introduced TVs also incorporate Intel's WiDi (Wireless Display) technology.

2. Streaming TV, Online Videos and Music:

I have found a goldmine of streaming video programs available over the internet. An excellent media player software for watching free streaming TV shows and videos is the open source XBMC program that can run on Windows and OSX platforms; you can download it from here. iTunes, Boxee, Hulu, and Kylo are some of the other programs that allow you to organize and view hundreds of TV programs and podcasts, all on demand.
You can also add a relatively low-cost monthly Netflix or Amazon Prime account for watching a large collection of movies online as well as on DVDs. Many people already have a broadband cable or DSL service which just sits there unused when not browsing the web or doing email, so why not put it to use?
Watch 1000's of free downloadable iTunes podcasts of favorite TV shows. To set up iTunes on your Media Center read this post.
Listen to the millions of tracks of free streaming music available via Pandora and Spotify.
File all your music: Organize and listen to your mp3 music collection
JPEG Photos: Categorize, store and play back all your digital photos.
Scan, save and preserve all your valuable old 35mm photos and slides into a centralized album.

Roof-mount do-it-yourself antenna
(click to enlarge)

For the more technically inclined - build your own HTPC Media Center!

"HTPC" stands for Home Theater PC. It is basically a dedicated PC that you build or buy consisting of the necessary Media Center software, an HDMI or DVI graphics output connector and a one Terrabyte or larger large hard drive. Attach this to your flat-screen TV set or monitor and you now have the essential requirements for a dedicated entertainment / media center "hub". A compact full-featured Home Theater PC Media Center can be assembled with standard components purchased online from Newegg and Amazon.

My DIY Media Center
(click to enlarge)

Do It Yourself? I enjoy the challenge of a rewarding DIY project and like to save money as well. I have built several Media Center HTPCs before for myself, family and friends. This time around, I decided to build one and describe the steps in this blog as I go along. Those of you who are hesitant to build one yourself, or just want to know more about the subject are welcome to follow along. Of course, the following notes and suggestions are based on my own experiences, so I am not responsible for any problems or consequences resulting from your use of this information!

How to start, what do I need and what will it cost? The following is a list of the parts I ordered from various online stores. At time of purchase, the total cost of all parts (not including the Windows 7 Home Premium O.S.) came to just over $500. Your own costs will probably end up being different based on availability and the parts you select. This build is based upon my own research but there are many possible variations. Let me know about your own experiences!

The Operating System: I have built several HTPC Media Center boxes, all based on Windows 7 Home Premium. The Media Center software installs automatically when you first install the Windows OS. Most people can find a "System Builders" copy under $100.
Update: According to this link, the new Windows 8 does not include Media Center as part of the basic package, however it is available as a post-install optional piece of software.
Which version of Windows 7, 64-bit or 32-bit? 32-bit processors are limited to 4 GB of memory, and typically can't use the full amount. The newer Intel 64-bit processors are theoretically capable of referencing 2^64 locations in memory, or 16 exabytes, however, all 64-bit versions of Microsoft operating systems currently impose a 16 TB limit on address space and allow no more than 128 GB of physical memory. I have installed the 64-bit version of Windows 7 in my recent Media Center HTPCs builds and I have noticed better performance. If you have at least 4GB of SDRAM, or are looking at the larger 8GB versions, then be aware that 64-bit Windows 7 is designed to make use of all that RAM efficiently. Make sure first that all your hardware (i.e., tuner or graphics cards) have the necessary 64-bit compatible drivers available.

Xbox Universal Remote Control

RC6 infrared USB Receiver

"The 10' Viewing Experience" using a Remote Control: Since the whole idea of a Media Center is to be able to sit at a comfortable viewing distance, you will need a suitable remote and a USB infrared receiver. I bought a Microsoft XBox 360 Universal Remote Control that can be integrated nicely with Media Center. It has ergonomic lighted buttons, fits nicely into my hand and is cheap. I also found an RC6 InfraRed USB Receiver on eBay. Some registry tweaks are required for this remote to work with Windows Media Center. Follow this link for the setup procedure. The following website: http://wiki.xbmc.org/index.php?title=Remote_Control_Reviews also has gobs of useful information about other Media Center compatible remotes.

Another Remote Control option: The Flirc Media Center Remote Control Companion Adapter: This nifty little device plugs into an available USB slot on the front of your Media Center and allows just about any TV remote you may already own to be adapted to work with your media center HTPC. It comes with the necessary software required. According to the manufacturer: Flirc learns any remote control, not caring about different vendor protocols. Just walk through our super simple setup pairing individual remote buttons with 'Media Center Buttons' and you're done

Wake-up from "S3 Sleep Mode": The Remote Control's ON/OFF button will cause the system to go in and out of low-power sleep mode. This mode is an important requirement for Media Center, since it allows automatic Record and Guide Downloads to occur at pre-determined times and the system goes back to sleep when done. In case of a power outage, or if the box is unplugged, the sytem requires a "power on startup". In other words, the remote control cannot be used to bring it back up and you have to use the power button. I also keep a mouse and keyboard handy for initial setup and occasional debugging.

The Mini-ITX Case:

Athena Mini-ITX Case
With 150W Power Supply.

I wanted the smallest case that could comfortably house a mini-itx motherboard with adequate room to mount the stock Intel heatsink and could fit easily on a bookshelf.

For several HTPC builds I selected the compact and sturdy Athena Mini-ITX Case from Amazon measuring 10.28" x 7.87" x 6.54". It includes a 150W power supply and a quiet 80mm fan. Refer to this link for a detailed step-by-step assembly video.

Apex MI-008 Tower Black P4 Chassis

The Apex MI-008 is another inexpensive mini-itx case that I have used for several recent builds. It measures 15.2 x 11 x 7 inches, and includes a 250W power supply. There is no built-in chassis fan, instead the power supply's fan serves to exhaust air out of the case. Since it sits right on top of the CPU there is barely enough clearance between the Clarkdale CPU's stock fan and the power supply, but the Sandy Bridge CPU/stock fan fits underneath with virtually zero clearance. With the Apex case I found it impossible to mount the hard drive in the lower bay beneath the DVD drive, so I opted to mount it vertically along the right hand side with the black plastic rail provided. Mounting the DVD drive requires removal of the black front panel and I had some difficulty mating the drive's eject button with the recessed button, I had to shave down some protruding plastic in order to get the drive close enough to the front.

The Cooler Master Elite 120 is a High-Quality Low-Cost Case

The CoolerMaster Elite 120 Advanced is my favorite case for a general-purpose mini-IX build, and I ended up using it for my current desktop office computer.
I paired it with a Gigabyte 1155 H77N Mini-ITX motherboard and an Ivy Bridge Intel Core i5-3330 Quad-Core Processor for a powerful expandable system.
I also included a 128GB Solid State Drive and 8GB of DDR3 RAM.
This excellent high quality case is large enough to fit all necessary components nicely, without any of the hassles of the other low-cost mini-itx boxes I have used. Note that the case comes without a power supply, so you will need to purchase a separate ATX power supply for it.

Mini-ITX Motherboards and CPU alternatives:

Mini-itx motherboards have a small 6.7" x 6.7" form-factor and are well suited for low-power, compact HTPC and desktop computer builds.

Built-in HD Graphics: You won't need an additional graphics card with the Ivy Bridge, Clarkdale or Sandy Bridge compatible motherboards that feature direct video CPU outputs. The usual on-board graphics chipsets have been left off since they make use of the integrated graphics cores built into Ivy Bridge, Sandy Bridge or Clarkdale CPUs. Only the necessary interface from the CPU's graphic chip to the 3 rear-panel HDMI, DVI and VGA video connectors is included.

As described above, my most recent build uses the Gigabyte 1155 H77N Mini-ITX motherboard with an Ivy Bridge Intel Core i5-3330 Quad-Core Processor. These two elements combine to make a compact low-power yet powerful multi-purpose desktop and HTPC system. The Gigabyte H77 motherboard has dual hdmi ports, and also incorporates the mini PCIe Intel Centrino Wireless-N 2230 card which offers both 802/11 b/g/n and Bluetooth 4.0 support. With this module, Gigabyte also provides the necessary drivers to enable Intel compatible Wi-Fi/WiDi (Wireless Display) - a really neat feature!

I have also used the Socket 1155 Sandy Bridge Intel Core i3-2100 3.1GHz CPU featuring Intel® HD Graphics 2000/3000, DX10.1, Pixel Shader 4.1 and Blu-ray Stereoscopic 3D with HDMI 1.4 with the Biostar TH61, ASRock H67M-ITX and Gigabyte GA-H67N-USB3 mini-ITX motherboards - all have built-in HD graphics outputs.

Intel's Wireless Display (WiDi) allows you to wirelessly connect your HTPC to a compatible TV - no more awkward wiring via HDMI cables! New TVs are shipping with WiDi support, but for most other TVs you will need a WiDi adapter, such as the Belkin ScreenCast, NetGear Push2TV, or the D-Link Mainstage. Gigabyte's H77 / Z77 series motherboards include a half-size PCI-E module that supports Intel's Wireless Display. You must install Windows 7 to allow this feature and you should download the latest version of the Intel WiDi Widget.

Note that you must pair Intel LGA 1155 socket compatible motherboards with the Ivy Bridge and Sandy Bridge CPUs!

My older builds were with the Gigabyte GA-H55N-USB3 paired with a lower cost Intel Core i3-550 Clarkdale CPU LGA 1156 socket compatible motherboard.

Other Components:

DDR3 RAM: I used a pair of compatible 4 GB Corsair DDR3 1600 SDRAM
Hard Drive: Recorded TV and photos gobble up storage space rapidly, so I decided to get the largest hard drive I could afford. I selected this Seagate Barracuda 2TB 5900 RPM drive.
Solid State Drive (SSD): I included an OCZ Agility 3 AGT3-25SAT3-120GB SSD in my latest build. This unit really speeds up access and boot times and allows for noiseless operation - all I can hear is the cooling fan. I used the SSD as the primary drive only for the Windows 7 OS installation. All the other media, including the Media Center recorded TV, is redirected to the 2TB hard drive.
DVD / CD Burner: I am using a Liteon CD/DVD Blu-Ray Drive. there are blu-ray licensing issues with Windows 7 Media Center, but the latest version of PowerDVD does provides an interface from within Media Center to PowerDVD.
TV Tuner Card: In my case, this was the most critical requirement for watching and recording "cable-free" ATSC TV programming. I wanted a dual tuner card that could allow me to record two programs simultaneously, or record one program while watching a second. I selected this Avertv MTVHDDUWB HD Duet PCI-E card. It plugs into the single available PCI-E slot on the Gigabyte motherboard.

DIY Videos: Refer to following additional links for step-by-step videos and detailed information to assist you with building your own Media Center:

For those of you who have never built anything like this before and could use further help and/or clarification, email me, or post your question in the comment box below.

Tell us about your own Do-it-yourself Media Center Set-up Experiences - or get answers to your questions!

Building your own Media Center is almost always a learning experience. Let others know about some of the things you may have learned or provide us with hints that may be helpful to those attempting a build for the first time.

Leave your comments and/or questions by clicking here: Comments. Thanks!

The next post describes the HTPC Media Center assembly process.

Monday, November 10, 2014

Add a DIY Audible Alert to Motion-Sensing Security Lights with Remote Intrusion Monitoring

Heath Zenith Motion-Sensing Flood Security Light

Replacement Motion Sensor Head

Commercially available Motion Sensing Security Lights work really well. They are inexpensive and relatively easy to install. I was able to pick up a couple of clearance units through Amazon for around $12 a piece. I have installed these around the perimeter of the house, and I have been surprised at how effective they are as a deterrent to unwanted intruders. In my case they also help to keep out hungry mule deer that love munching on my wife's favorite plants at night! The units can be set to come on at night only when motion is detected, and feature a range control and on-time adjustment for 1, 5, or 20 minutes when set to "Auto" mode. The stand-alone Replacement Motion Sensor Head comes without the two lamp sockets. It allows you to wire up directly to your existing wall mounted lights or to the primary side of the transformer of series connected low-voltage pathway lights.

What's Missing: A nightime audible alert feature with remote monitoring option

Unavailable in commercially available units is some form of a "short single beep" audible alarm to scare off particularly stubborn intruders and large animals; it should also warn me remotely of intrusions into the back yard, or when someone pulls into the driveway at night. Following is my "wish list" of requirements for a suitable unit:

It should be simple and fun to build and a cost less than unit(s) currently on the market.
It should attach easily on to the existing motion sensors that I already have installed around the house.
It should sound only once at the beginning when the lamps come on. Ideally, the audible alarm should be loud enough to be heard a short distance away to scare away intruders, but not to disturb neighbors.
It should allow the intrusion to be monitored from within the house. At first I assumed that the beep would be loud enough to be heard at some distance from the sensor head, but I later realized that the only way to accomplish this would be to have a wireless remote monitor unit installed indoors.
The indoors monitor unit should produce an audible beep - ideally the beep duration should be different for each sensor. It should also provide a visual indication of which of the motion sensors has been activated via a different colored LED for each motion sensor.

Here are a couple of solutions:

1. The Basic Beeper:

DIY "Basic Beeper"

The first units I built are attached directly to the red and white wires of the individual motion sensors - one near the driveway and the other 2 around the perimeter of the house. I set them to a volume level that doesn't disturb the neighbors or wake someone sound asleep. Building this basic unit should be an easy project for anyone with a little electrical / electronic experience. Take normal precautions and observe local electrical codes when hooking up wires to the hot and neutral A.C. line; verify your wiring carefully and remember to turn off the circuit breaker first! For further details on the "Basic Beeper" go here.

2. A Flexible Wireless Remote Intrusion Monitoring System:

433 MHz Motion Sensor Sending Unit

Indoor Receiver Monitor

It quickly became apparent that several of the Basic Beepers I installed were inaudible from inside the house. To solve this I came up with the following simple wireless remote monitoring system comprised of two basic modules - A 433Mhz Transmitter Sending Module (shown below) connected to each of the existing motion sensor heads, and one or more Remote Wireless Receiver Monitor boxes (see below) located indoors. Each monitor box consists of a simple low-cost RF receiver module connected to a small piezo-electric beeper and multicolored indicator LEDs that monitor the status of up to 8 remote devices, which can be the above-mentioned motion sensor lights, or optionally, several magnetic intrusion sensing switches that may be attached to exterior gates, doors or windows. For further details on the Wireless Monitoring System go here.

Getting Started - Understanding the Motion Sensor's Wiring:

Heath / Zenith Sensor Head Wiring Diagram
(Wiring is the same for the
stand-alone Replacement Sensor)

I first needed to figure out how to tie my alert into the motion sensor's wiring. Most commercial units come pre-wired with a sensor head and two lamp sockets. I used the stand-alone replacement motion sensor unit instead for my two existing wall-mounted driveway lamps. Wiring for both types should be the same. I mounted the sensor head separately to a 4" round electrical receptacle purchased at Home Depot in an unobtrusive location away from the lights themselves. Either type of sensor head has an extra red control wire in addition to the black (HOT) and white (NEUTRAL) wires coming out of it. The lampheads, or any optional load, must be connected between the RED and WHITE leads. According to the manufacturer, a small additional load can also be connected across these 2 wires.

On my unit the total load including the two lamp heads should not exceed 500W (or 4.2 A). Refer to the wiring diagram above.

The RED control wire has full line voltage applied to it only when the motion sensor activates. I connected the 2 wires of my alert across the RED and WHITE wires.
NOTE: Many motion sensors are intended to drive incandescent lamps and use TRIACs instead of relays in their output circuit. They may have difficulty driving inductive loads such as AC relays, LED bulbs or the 110V to 12V step-down transformer used in the Beeper. In such cases I add a simple Snubber circuit (refer to this link for design detail) consisting of a "Class-X2" rated 0.47uF/ 275VAC capacitor in series with a 51 ohm/5 Watt resistor. After soldering these 2 components together in series, make sure they are completely insulated with shrink tubing, and then connect the two ends of the series combination across the RED (load) and WHITE (neutral) leads of the motion sensor.

1. The Basic Beeper

If you don't need any remote monitoring, then one of the 2 basic versions shown below should work for you. The 2 circuits differ in the method used to derive the 12 to 15 Volts DC from the 117 Volt AC line. There are many power supply options for this, the easiest is to use a standard AC to 12VDC wall mounted power module - A quality, well-regulated power source produces the cleanest beep.The first version (Fig.1) includes a transformer-isolated full-wave regulated power supply, and the second "transformerless" version is shown in Fig. 2. Other than the power supply and regulator, both versions require only 5 to 7 inexpensive components, including the volume control Rv. All these are available online through Amazon or eBay.

My initial requirement was to emit a single loud "beep" only once at the beginning of an intrusion, as soon as the sensor lamps came on. I began by locating a couple of 12 volt D.C. electronic automotive back up alarms that I decided to put to use for this project. Similar units are

Auto Backup Alarm

widely available online or at any auto parts store. Most of these units produce a continuous annoying loud 97 dB one-second rate "beep - beep".

Piezoelectric Buzzer

A cheaper, quieter option is a small inexpensive piezoelectric buzzer that produces a continuous high pitched beep. The design challenge was to come up with a simple yet reliable circuit, with adjustable volume level that could terminate the sound after the first 1 -2 seconds. My first simple design used no transistors or relays, and was housed in a small plastic box located adjacent to the motion sensors. The total parts cost for this version (Fig 1 and 2. below) came to less than $15 using readily available components from eBay and Amazon. The remote monitoring board was somewhat more complex, and required adding a wireless transmitter function to each of the 3 remote sensor boxes.

How it Works:

As an inital experiment I attached a small 117 VAC to 12-14 Volt DC "wallwart" power supply directly to the beeper, and obtained a very loud continous beep. In order to get the single initial beep I needed, I took advantage of a basic property of an R-C (Resistive/Capacitive) circuit that sees a large fully discharged capacitor as a short circuit before charging up exponentially to full charge with an applied voltage in time (seconds) = R (ohms) x C (farads). This feature provides a brief burst of full current to the beeper, the capacitor then charges up to full voltage and the current to the beeper drops to zero.

I added a 2200uF / 16 volt electrolytic capacitor in series with my beeper (being careful to observe the correct polarity of both capacitor and beeper), and presto! I had the makings of my "one-shot beeper". With this basic circuit, I obtained one fairly loud beep (or "chirp" depending on the DC regulation of your 12-14V power supply), followed by several rapidly diminishing beeps.
Unfortunately, once the capacitor charges up fully and the motion sensor shuts off, the capacitor continues to hold its charge. This is the result of the very high OFF resistance path through the reversed-biased rectifier diodes in the circuit, and the high reverse resistance of the beeper itself. When the sensor comes on again, the beeper refuses to sound. This problem is easily solved by adding a diode and resistor across the capacitor C1 (fig. 1) or C3 (fig. 2) to provide a discharge path as soon as sensor power shuts off. This allows the beep box to be fully armed and ready to go before the motion sensor comes back on again.

Fig. 1: Transformer Isolated Beeper for Commercial Motion Sensors

Fig. 1 illustrates the "safe" transformer based version. It features a 12 volt voltage regulated power supply, or alternatively, a transformer-isolated AC to DC "WallWart" power supply with sufficient power to drive the much louder auto backup alarm.

Fig. 2: Transformerless Beeper for Motion Sensors
(Click to enlarge)

Fig. 2 illustrates the more compact "transformerless" version that utilizes the capacitive reactance of a "Class-X" rated" 0.47uF capacitor combined with surge limiting resistor R1 and two back-to-back Zener diodes D1, D2 to drop the AC line voltage down to approximately 15 Volts at 15mA. This output current is sufficent to drive a small low-power efficient piezoelectric buzzer that produces a fairly loud 3 KHz high pitched beep. Zener diodes D1, D2 are also connected in a bridge configuration with two "normal" diodes D3, D4 in such a way that each of the 2 opposing Zener diodes D1, D2 acts as a Zener reference diode during one 1/2 cycle of the AC waveform, and as a normal forward-conducting diode during the other half, producing approximately (15 - 0.6) Volts D.C. across the output of the bridge. During the positive 1/2 cycle, current ﬂows from the Hot AC line via Zener D3 through the load and back to the Neutral line via D2. During the negative half cycle it ﬂows in the opposite direction from the Neutral line via Zener D4 through the load and back up to the Hot line via D1. .Warning! Even though transformerless circuits are commonly used within many commercial motion sensor units, be aware that such circuits are connected directly to the AC mains supply! When the power supply is connected as shown, the negative rail is 0.7v above neutral through forward biased zener diode D2. Using a line tester with respect to earth ground, make sure that your HOT and NEUTRAL wires are hooked up correctly. If the Hot and Neutral lines are accidentally reversed, the negative rail will be 170v (peak) above the hot line and the current flow through the diode will be lethal and can kill! Irregardless of hookup, you should never come in contact with any part of this circuit. It is essential that this unit be housed within a suitably insulated enclosure. The completed unit is enclosed in a SERPAC WM033 plastic box.

2. A Flexible Wireless 8-sensor Intrusion Monitoring System

The Wireless Monitoring System consists of a homemade RF Transmitter Module connected to each Motion Sensor Head and a Central Receiver Monitor Box mounted indoors. I built several small circuit boards containing an inexpensive 433 MHz RF transmitter module and a digital encoder IC which I mounted inside small weather-proof plastic boxes powered by a small 12-volt AC Charger Module. I attached each one to the control and neutral leads of my Motion Sensing Security Lights. Now whenever any of the outside motion sensor lights comes on, its sensor head transmits an encoded RF signal to the Indoor Monitor Box which sounds a short beep and lights the associated color LED for the duration of the motion sensor lamp's ON time.

Holtek Encoder / Decoder IC pair

433 MHz Transmitter / Receiver Kit from Amazon

The Transmitter/Receiver design utilizes a pair of very inexpensive 433 MHz RF Transmitter + Receiver Link modules that I purchased from Amazon. I have previously used these on Arduino wireless projects - similar units are also widely available on eBay. These units worked well over a range of 50 feet with a simple 1/4-wave straight wire antenna 6.8" long. I was able to increase the transmitter's range significantly by using the simple Deep Dish Cylindrical Parabolic Antenna described at: http://www.freeantennas.com/projects/template/ (see photo above of transmitter with antenna).

The transmitter module is driven by the output of a Holtek HT12E CMOS Encoder IC, and the receiver module drives a matching Holtek HT12D CMOS Decoder IC. A pin-equivalent Encoder / Decoder IC pair made by SilvanChip is the SC2262 Encoder IC and the SC2272 Decoder IC; these are widely available on eBay.

Transmitter Module detail

Fig. 3: Sensor Head Transmitter Module
(click to enlarge)

Transmitter Circuit (Fig. 3):

Each Transmitter box contains a Holtek HT12E CMOS Encoder IC which drives a small 433 MHz RF transmitter module. When the motion sensor activates, it supplies power to the box, thereby asserting the TE/ (Transmit Enable) pin of the Encoder chip low. This generates an encoded pulse train containing an 8-bit address hard-wired code (A0 to A7). Note: In order to receive the encoded data correctly, the decoder chip in the Monitor Box must also be hard-wired with the same 8-bit address code as on the transmitter.

A unique 4-bit data word (D8 to D11) is also part of the serial data stream that is sent out to the RF transmitter module. Three of these 4 input data bits (D8 to D11) go to a 3-pin jumper plug that generates each sensor head's unique binary ID code (000 to 111). This code is decoded at the Receiver end and used to light the appropriate Sensor's LED. The 4th data bit input (D8) is wired to an RC (resistor/capacitor) network (R4 and C3 shown in Fig.3). The resulting time constant inserts a momentary "0" into the encoder's serial data word before its input pin charges up to a "1". This pulsed bit is decoded at the receiver to sound a brief "beep" at the beginning of the Sensor's ON period. The 4th LSB data bit (D8) at the HT12D encoder's output goes low only for a duration determined by the time constant of the resistor/capacitor (R4 and C3 in Fig.3) connected to the input pin of the transmitter's HT12E chip located in each of the 1 to 8 sensor heads. This low pulse is connected via a 2N3906 PNP transistor to an inexpensive piezoelectric beeper which produces a single adjustable volume "beep".

Fig. 4: 3-Sensor Monitor Receiver
(click to enlarge)

Receiver is built inside a small Altoids can

Receiver Circuit (Fig. 4): The monitor receiver consists of 1 (or more) small boxes powered by small readily available 5-volt USB cell-phone charger modules, and located indoors in various locations (I placed mine in the bedroom and kitchen). Each unit remains in a low-power standby state until it receives an RF signal from any of the 1 to 8 ensor transmitter heads. Each homemade receiver module consists of a tiny little low-cost 433MHz super-regenerative receiver module, plus two decoder / demultiplexer ICs. The receiver module demodulates the data stream and passes it on to a Holtek HT12D decoder IC. This chip strips off the repeating serial word consisting of 8 address bits and 4 data bits (D8 to D11) representing the unique binary coded state of the particular sensor head. If the 8 transmitted address bits (A0 - A7) match the 8 hard-wired address input pins of the decoder IC, then the decoder's VT (Valid Transmission) pin goes high and the 4 data bits are latched. Three of the 4 data bits (D9 to D11) are then passed on to the 3 input address bits of a 74HC138 3 to 8 decoder chip, which also serves as a buffer to drive the LEDs. The HT12D's VT signal goes to the positive enable pin (E3 ) of the 3 to 8 decoder. Depending on which sensor head's signal is being received, a "0" will be asserted at one of the 74HC138's eight output pins which are connected to a maximum of 8 different colored LEDs on the Monitor Box labeled SENSOR#1 through SENSOR#8. The corresponding sensor's LED will light up for the duration of the valid transmission.

Other Ideas

Multi-colored LEDs from Amazon

Adding multiple Sensor Monitor Boxes Indoors: All the components I used for this project are inexpensive and readily available. Several identical receiver boxes with matching address codes can be installed at very low cost in various parts of the house, such as the bedroom, kitchen, basement, office, etc. Each box will sound an adjustable volume beep and light a different colored LED corresponding to the motion sensor that was triggered.

Centralized Outdoor Intruder Alert: You can also install one or more receiver boxes in a more effective location outdoors to serve as the central audible intruder alert that will sound for up to 8 Motion Sensors Lights or other intruder sensing switch contacts. You will need to build a receiver board with matching address and a beeper only. I suggest mounting these inside a weatherproof receiver box.
I mounted each of the remote transmitter "Heads" in a small plastic box and connected it to the associated Motion Sensor head's control and neutral leads via a 117 V to 12 VDC power adapter.

Solid State Relay
controls large AC loads

Adding additional remote controlled spotlights & lamps: By adding a low-cost solid-state relay in place of the beeper and series resistor shown within the Sensor Receiver Monitor Box (see Fig.4) you can turn on a remotely located floor lamp, spotlight, or some other AC load whenever any of the outside motion sensors activate. Mounted indoors, this can serve as additional warning to intruders when they see an inside light come on. The input side of the solid state relay presents a 4-5mA load to the decoder. The output side can drive an AC load up to 25A at 250VAC. The load requires a suitable female AC outlet; this is wired in series with the 2 output screws of the relay and the two sides of the AC source.

Battery powered transmitter modules for other applications: By replacing the transmitter module's 12v dc power supply and regulator IC with a small alkaline 9V battery, a host of other remote sensing applications are possible. When the TE/ signal going to the HT12E Encoder IC is high, power consumed by the transmitter module drops to less than 1 microAmp, making this module ideal for battery powered applications. Replace the shorted Test Jumper shown in schematic in Figure 3 and wire it to a suitable normally open magnetic contact switch, and you have a highly effective wireless intrusion detection system that you can add to vulnerable garden gates, exterior doors, and windows.

If you need help or more information about building your own "Beep Boxes" contact me at viewcrestechnology@gmail.com.

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