I just bought and built this kit. My kids love it and I had fun making it. I’ll be using it in my office to keep coworkers from sneaking up on me since my back faces the door and I find myself startled after to much coffee and when I’m concentrating. Much to the amusement of my coworkers! Anyway; My question: Why is there so much “stuff” on the transmitter board? (I know NOTHING about electronics, so go easy on me). In playing with this kit I found pointing a TV remote at it and pushing a button gets the alarm beep to go off and on as the the remote IR light flashing its signal. Making it seem any IR source will work. So couldn’t the transmitter be a few IR LED’s hooked up to a battery? Why all the resistors, capacitors, transistors, etc…
Because the IR signal is modulated. If the receiver would respond to unmodulated light, it would never beep as sunlight, artificial light etc… contains IR light.
Ok, I think I understand. Now my next question(s):
I’ve been using the device with much success and amusement for me and my coworkers for a few days. My office has a double door so the device is about 8 feet apart. Before a full day the device seems to lose power (I’m using 9v batteries). What I mean is the buzzer will start to “growl” as though it’s not seeing the IR LEDs very strong. In trouble shooting, in my non-electronic educated way, I’ve bent the IR LEDs slightly which sometimes seems to get it working again. But eventually even this doesn’t work. I then tried moving the device closer together by mounting one part on the door that normally does not open. This worked for a few more hours, but the “growl” came back.
Holding the device even closer still makes it work again. So my guess is the batteries are wearing out, but so soon? How long should a 9v battery power this kit?
I’m having fun with these kits, I’ve bought three more, which I’m sure will get me back here for more questions and answers!
Thanks for the help!
Please note that battery operation is only for testing/demonstrating.
Consumption is too high for continuous battery operation.
For actual use, we recommend a regulated 9V power supply for each unit.
I wish not to jack this thread, but I would know how I should go about powering this kit with different power sources, specifically a 7.5V supply or a 12V supply. I noticed how little power they are using, so I figured if I can somehow drop the voltages on the 12V supply with a resistor with a 0.5W rating to close to 9V, would this work? Also, how would the 7.5V supply affect the kit? My guess is that it will only impair distance, but that’s no problem as I won’t be using it for distances of more than 1m~1.5m anyway.
Thoughts? Tips?
Kit will not work in a reliable fashion with 7.5V.
9-12V should not be a problem.
I tried connecting a used 12v DV power supply to my receiver. Upon turning it on it beeps for a moment and the LED lights but it fades out and the beep “dies” out as well, as though it is being turned down. Moving the power plug around in the connector on the circuit board seems to get a “random” connection but still only a beep which fades away… any suggestions?
This points to a bad connection. If necessary, replace DC connector.