12v RELAY & HEATER CIRCUIT

[TIMBO]

Hi guy's, As said in the other post i am going to do some foot switching via a relay setup rather than just turning the circuit OFF by disconnecting the tube at the cathode.

I've had much success running the heaters on 12v AC (NO HUM) so i can run the tubes on 12.6v DC (9vx1.4= 12.6v)and the relays as well. I also have LEDs for indicators.

By my calculations the tubes should draw about 1.6A and my heater transformer is rated @ 2A, this leaves me with about .35A and from what i can find i think a 12v relay draws about .044A (does that sound about right) so i think all should come under under my 2A.

Question:- When using the 12v AC heater circuit i added an artificial CT, When using a DC supply i am using a half wave rect to the tubes as well as the relays, can the tubes heaters be powered this way??

Has anyone had problems with having the relays mounted near other circuit components (the nearest components are the 12ax7s cathode cap/resistor.

I'm using a 4700uf cap for filtering is this enought?? Thanks
 
SHEET 5 is where to look 

[kagliostro]

Just a consideration

if your transformer winding is rated 9v 2A = 18VA

and you rectify --- 9v*1.4 = 12.6v

18VA / 12.6v = 1.428A

---

About relay near components read this

http://www.el34world.com/Forum/index.php?topic=13066.0

K

[EL34]

Check out my new relay board idea here

http://www.el34world.com/Forum/index.php?topic=14468.0

[RicharD]

>When using the 12v AC heater circuit i added an artificial CT, When using a DC supply i am using a half wave rect to the tubes as well as the relays, can the tubes heaters be powered this way??

No.  With a 1/2 wave rectifier, one side of the transformer secondary is grounded.  Your 2 balancing resistors are grounded at their common point.  This means 1 resistor is grounded on both ends and the other is now a Heavy bleed resistor (unnecessary load).  Beef it up, go full wave with an appropriate dropping resistor and use DC for controls and filaments.... or step up to the pump and build a regulated 12VDC supply.

[DummyLoad]

1/2 wave will be noisy. 9V secondary with FWB with 1A current demand won't make but 10V (simulated). PSU designer indicates even less ~7V.



--DL

[TIMBO]

Thanks guy's, I'm a bit mift with this one, I used 12vac on the heaters on my last build and had no hum peoblems and i can easily get all tubes except one that does not have a 12.6v heater under 2As, But that is OK. So rethinking how i am going to do this is similar to what boogie do on the rectifier and that is to run the tubes as normal on a CT 6.3v (but i'll run at 12v CT) than to a FULL WAVE rect to a voltage regulator (12v) for my relays.

So the tube that has the 6.3v(.45A) i'll use another transformer for this only. Thanks