Electronics

[Bax]

Who here has stuffed around with electronic circuits in the day? Or of late?

I've got to make a circuit that detects Battery voltage between 10-14 volts from a 18v Source. I've got the window detector and I've got that no dramas.

My problem is that afterwards - if V is between 10-14V then I want a Green LED to be lit. If V is <10 or >14 I want a buzzer to sound.

So thats where my dilemma lies, the window detector spits out 2 wires for my line diagram, I want to put it into another comparator and seperate. But I just can't figure out how to wire it. I'm not quite sure on how to use the LED as the transistor effectively.

Help?

[gopher]

i've stuffed up a few circuit boards in my time

[Lost_Pete]

Making a lot of assumption here. Such as the output of your circuit can drive both high and low signals. Now assuming your window detector circuit does the following;

10 - 14V there is a high output from your circuit
<10 or >14V there is a low output from your circuit

You can use the output to turn on a LED by connecting a LED plus resistor from the output of your circuit to ground. The anode of the LED is connected to your output.

For the buzzer (assuming a low current piezo) you connect the positive of the buzzer to +12V and the negative of the buzzer to your output. Then when the output goes low it will turn on the buzzer.

A few more details of your circuit would help.

regards
Pete

[Bax]

Pete your a champ, you've reminded me of some things I've been neglecting.

What more would you like to know about my circuit?

10-14 shoots at a high, outside shoots out a low, correct.

Low current piezo would be correct. I was previously trying to set it up with a nand gate and a series of inverters. but my brain isn't cooperating with me tonight.

if I bring an And gate in to combine the two high outputs to another high, and anything else a low output that lets me spit it out the way you described above I guess.

I had it sketched into Multisim before but it froze on me and I lost my circuit.

Oh well, back too it.

[stocky]

you would use a parallel circuit with sets of led and resistors in series i would think. different value resistors would result in a different voltage drop across each different branch. im probably wrong but if it wasnt this late id help you out more.

[Bax]

I'm having a stupid moment, I need to measure current at the output of a Comparator, what do I need?