Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: punkykatt on December 06, 2010, 09:36:19 am

Title: LED on 3.15vac?
Post by: punkykatt on December 06, 2010, 09:36:19 am
Hey Guys. Im building a simple a/b switcher for a local band. The switcher has a small transformer with a  6.3v @1.2A with CT secondary winding. CT grounded one leg will power the switching relays. Can I use the other leg to power a 1.7v .040mA LED? Do I need to convert the AC to DC?  I know very little about SS stuff. I found on the net you can run LED`s off 120vac with a cap , resister and 1N914. I want to put this LED on  a foot switch, would that be safe?  Any help is much appreciated.   Punky
Title: Re: LED on 3.15vac?
Post by: LooseChange on December 06, 2010, 10:41:34 am
Run it on AC. You need a small resistor in there to limit current.
Title: Re: LED on 3.15vac?
Post by: PRR on December 06, 2010, 04:14:36 pm
> one leg will power the switching relays

With what, 3V AC ??

Small relays are almost universally DC. Betcha you gonna have DC in there before you done. Probably at least 5V DC (tough from 3V AC). I think when you have the relays working, feeding the LED will be trivial.

In some other case where only 3V AC is available: try RED and 100 ohms. Fast head motion will reveal 120Hz flicker, NBD.
Title: Re: LED on 3.15vac?
Post by: punkykatt on December 06, 2010, 08:09:18 pm
Thanks PRR,   The relays/switches are on a Weber board kit. 

Below is from Weber  site:

 Channel Switch board, low power, 4 independent channels, kit. This board has the same labeling, dimensions, mounting, and pinout as our CHANSW boards above.
However, this board does not require that the switch lines be isolated from ground. Power is supplied from one side of the 6.3VAC filament winding. The centertap of the filament winding must be grounded or a separate 3 to 6 V AC source must be provided. A ground applied to the switch input to the board actuates the relay.