Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: phsyconoodler on May 06, 2010, 12:22:50 pm

Title: using filament supply to operate 5v relays
Post by: phsyconoodler on May 06, 2010, 12:22:50 pm: I am building a two channel amp and I already have the relay board built with 5v omron relays.I was wondering if I can use the filament supply to power these relays?
The Pt has no 5v winding and has tons of current capacity for the filaments.
I guess it would be like a DC heater arrangement,but how would one add a regulator in that circuit?I only need one wire to go to the two relays.
:smiley:
Title: Re: using filament supply to operate 5v relays
Post by: sluckey on May 06, 2010, 12:41:22 pm: Look here...

http://www.el34world.com/projects/relay_switch.htm
Title: Re: using filament supply to operate 5v relays
Post by: phsyconoodler on May 06, 2010, 01:55:17 pm: Sluckey to the rescue!And Doug of course.

Now,not being well versed in solid state circuits,I am using two relays and two LED's in the footswitch.With a 5v supply I get 14v after the rectifier and it works perfectly for this setup.Will the extra voltage from Doug's setup be ok with the 5v relays or should I get it down closer to the 14v I normally use?
Title: Re: using filament supply to operate 5v relays
Post by: sluckey on May 06, 2010, 04:25:44 pm: With a 6.3vac input, a bridge would put out about 9vdc. I would not be comfortable running a 5 volt relay coil with 9 volts. It's very easy and cheap to add a 5 volt regulator chip to the bridge output.
Title: Re: using filament supply to operate 5v relays
Post by: rzenc on May 06, 2010, 05:54:20 pm: Quote from: sluckey on May 06, 2010, 12:41:22 pm
Look here...

http://www.el34world.com/projects/relay_switch.htm

I had great results with this arrengement, just fine from drawing provided by Mr. Hoffman to implementation and tests.... no switching noises - pops - and it was used to engage overdrive section based on *umble circuits. It powered the relay and a red LED on the pannel, works beautifully. It's running for more than a year regularly. No complaints at all.

Rzenc
Title: Re: using filament supply to operate 5v relays
Post by: phsyconoodler on May 06, 2010, 07:05:06 pm: I should mention that the 14v is without any load.
I also have been using this arrangement(5v tap) for years with no problems either.Keep in mind I'm using two relays and two LED's.Does that make the difference?
The relays draw about 35ma each and not sure about the LED's.
Title: Re: using filament supply to operate 5v relays
Post by: RicharD on May 06, 2010, 07:40:39 pm: Protection diodes are your friends.
Title: Re: using filament supply to operate 5v relays
Post by: JayB on May 06, 2010, 08:03:37 pm: Those relays will kick in after 3v. I use two of them on full rectified 6.3ac which I get about a little over 5v. Works pretty darn good. They have a max voltage and I can't remember what it is.
Title: Re: using filament supply to operate 5v relays
Post by: tubesornothing on May 06, 2010, 09:04:29 pm: I am a chicken - I use the regulator as well. I never know what kind of power the guy might plug into.