Search found 7 matches

by VacuumTube194
Mon Feb 07, 2011 1:15 pm
Forum: General Discussion
Topic: Circuit for keeping voltage below a certain amount
Replies: 7
Views: 1716

Re: Circuit for keeping voltage below a certain amount

About 50-100 miliAmps.
dyarker wrote:how much current we need to dump?
by VacuumTube194
Mon Feb 07, 2011 9:58 am
Forum: General Discussion
Topic: Circuit for keeping voltage below a certain amount
Replies: 7
Views: 1716

Circuit for keeping voltage below a certain amount

I need a circuit that will maximize a voltage. What I mean is the voltage may vary, but I want it
so if the input goes above 30 volts, then it will send 30 volts only through the output. I don't want the
voltage cut off (like a fuse) if it goes above that amount. Does anyone have any suggestions?
by VacuumTube194
Wed Jan 30, 2008 12:02 pm
Forum: General Discussion
Topic: Building simple amplifier using 386 Amplifier chip
Replies: 5
Views: 1413

Its the 386 Audio Amplifier (typical application) in the Forest Mimms Radio Shack books, page 11 in my copy (though mine is from the 80's). Basically its just the 386, a capacitor and variable resistor. There is no sound without an input, but when the input goes in sometimes the audio is good and ot...
by VacuumTube194
Wed Jan 30, 2008 8:36 am
Forum: General Discussion
Topic: Building simple amplifier using 386 Amplifier chip
Replies: 5
Views: 1413

Building simple amplifier using 386 Amplifier chip

I built a simple audio amplifier from a 386 amplifier chip. The sound coming out of the speaker is not too bad, but sometimes a little staticy. Is there a way to cut down on the static? Also would piping the signal through an audio transformer help? Should the transformer be before the chip or after...
by VacuumTube194
Sun Jul 01, 2007 5:14 pm
Forum: General Discussion
Topic: Capacitance of variable capacitor for FM radio?
Replies: 8
Views: 2168

Interesting, I'm thinking the solution might be to design a capacitor circuit that gets me into the 160 range, and design it so one of the variable capacitors will only very slightly change the capacitance, keeping the frequency between 160-161 or so (since the NOAA channels are slightly different p...
by VacuumTube194
Sun Jul 01, 2007 1:50 pm
Forum: General Discussion
Topic: Capacitance of variable capacitor for FM radio?
Replies: 8
Views: 2168

Thanks

Thanks for the response. I can cannabalize one, but then I don't know the exact capacitance. My project is that I am trying to turn an FM radio into a weather band radio ( in the 160 or so MHz range ). I was hoping to use a second tuning capacitor in either series or parallel to bump up the receivin...
by VacuumTube194
Sun Jul 01, 2007 6:40 am
Forum: General Discussion
Topic: Capacitance of variable capacitor for FM radio?
Replies: 8
Views: 2168

Capacitance of variable capacitor for FM radio?

I would like to know the capcitance range of the variable capacitor in a typical FM radio, in Farads. Also, is there anywhere to buy those variable capacitors (the square white ones you see in the radios).

Finally, is there an electronic meter that can measure capacitance?

Thanks.