T&L Publications

If the alarm output can sink as well as source, you could connect the second LED in reverse of the first and connect it to the opposite polarity voltage. I assume the alarm output goes positive to light the first LED, which has it's cathode connected to ground. You would connect the second LED anode...

What is the low voltage point? If you send your schematic, I may be able to suggest a modification. [email protected]

Try a google search!

150 ohms should work.

The receiver is probably not tuned to the transmitter frequency. Try tuning the receiver for max signal.

The inputs have to be at least 1 volt above ground. If you are measuring the voltage, just move the sense resistor up the divider by 1 volt.

Why not use a PGA (progammable gate array)?

You may be thinking of "chopper stabilized op amp". The LTC1050 is an example.

Which approach is least expensive depends on how many you will produce. A digital signal processor would have the lowest component cost but the development cost would be higher than an analog approach. I am not willing to pay for a long distance phone call, how about an email address?

I buy from Mouser because they have a broad line, no minimum order and prices are good. You can sometimes find bargains at Jameco or All Electronics, but the selection is limited.

Answers to your questions:
1. yes
2. no, 2n54-- is rated at 800 mA, lamp draws 1 amp. Use Teccor #TCR22-4.
3. Use two lamps in series to operate on 12 volts.
4. Yes, buzzer works from 3 V to 15 V.

most AC motors are synchrounous with the AC frequency and cannot be speed controlled, except by changing the frequency. Why not use a DC fan?

The circuit is at: http://www.geocities.com/russlk/limitckt.jpg
You will have to copy and paste the URL in the address bar, geocities does not allow links.

You only need one DPDT relay, configured to run the motor one way when energized, the other way when de-energized. Place the limit switch in series with one of the relay contacts to stop the motor. The other limit switch is in series with the other set of contacts. The motor will run when the relay ...

Well, you could subscribe to Nuts & Volts. The local library is always a good source, and Radio Shack usually has some basic books.