help finding 115/230 primary to 12v secondary relay tranny

[Tonegeek]

Prefer flying leads. The biggest catch is I need to be able to switch the mains voltage to the relay and main power tranny using one dpdt voltage selector switch. I found one small 1/4 amp tranny but it is a dual primary so I can't switch it with the DPDT switch. I won't run my relays off the heater wiring no matter how tempting it is due to noise, and there is no 5v tap or I would try that.

[martin manning]

What does the primary on your main PT look like? Is it a dual or a multi-tap?

[alvarezh]

I've read on the forum knowledgeable individuals complain about the noise issues by obtaining relay power from heaters.

I am not qualified to overturn their opinion but I have built three amps with the attached schematic and have not found any issues at all.

The topology is from a Marshall 2550 (Silver Jubilee), I have not read anywhere any complaints with noise issues with this design.

OTOH, if you don't want to take any chances, here are a couple from Radio Shack. I can't get their site to load correctly:

http://www.radioshack.com/product/index ... Id=2102702

http://www.radioshack.com/product/index ... cale=en_US

Check the bottom of the loaded pages for more.

Hope this helps.

[ToneMerc]

Prefer flying leads. The biggest catch is I need to be able to switch the mains voltage to the relay and main power tranny using one dpdt voltage selector switch. I found one small 1/4 amp tranny but it is a dual primary so I can't switch it with the DPDT switch. I won't run my relays off the heater wiring no matter how tempting it is due to noise, and there is no 5v tap or I would try that.

http://www.mouser.com/ProductDetail/Tri ... OQL3NIs%3d

Configure relay supply as a doubler like HAD

TM

[martin manning]

TM, the description of that PT says "dual primary." On the data sheet there is no diagram but the description (referring to all transformers listed) says "single primary with single and multiple secondaries." Do you know if the primary is a series/parallel for 230/115 or a single winding?

[Tonegeek]

TM, the description of that PT says "dual primary." On the data sheet there is no diagram but the description (referring to all transformers listed) says "single primary with single and multiple secondaries." Do you know if the primary is a series/parallel for 230/115 or a single winding?

In addition the product picture shows only 2 leads coming off the primary which indicates it is not a universal. I never trust the pics, but still there are 3 possibilities. If no other solution comes up, I will call Mouser.

[martin manning]

Is your main PT a dual primay?

[ToneMerc]

TM, the description of that PT says "dual primary." On the data sheet there is no diagram but the description (referring to all transformers listed) says "single primary with single and multiple secondaries." Do you know if the primary is a series/parallel for 230/115 or a single winding?

Sorry, I failed to see "dual primary"...reading is fundamental . This diagram corresponds to the 70's vintage F313X that I have.

TM

[Tonegeek]

I've read on the forum knowledgeable individuals complain about the noise issues by obtaining relay power from heaters.

I am not qualified to overturn their opinion but I have built three amps with the attached schematic and have not found any issues at all.

The topology is from a Marshall 2550 (Silver Jubilee), I have not read anywhere any complaints with noise issues with this design.

OTOH, if you don't want to take any chances, here are a couple from Radio Shack. I can't get their site to load correctly:

http://www.radioshack.com/product/index ... Id=2102702

http://www.radioshack.com/product/index ... cale=en_US

I have used the RS trannies but they are only wired for 120v primaries.

I believe deriving power for relays off the heater will work in some situations. I had no problem switching channels but when I switched signals early in the signal chain (like lifting the stack or mid boost) is where it picked up some noise. I read that it could be caused by the switching transients in the rectifier getting into the heater circuit. I was using a doubler circuit for 12v relays. It would make life easier if i cold use that circuit especially as I need to accomodate 120v and 230v power.

[Tonegeek]

Is your main PT a dual primay?

No, single with taps for voltage selection.

[Structo]

I used this tranny for my 100w Dumble relay supply.

http://www.mouser.com/Search/ProductDet ... y553-F114X

[Tonegeek]

I used this tranny for my 100w Dumble relay supply.

http://www.mouser.com/Search/ProductDet ... y553-F114X

Close, but no cigar. I need it to work in the UK too

[alvarezh]

Guess I was more asleep than awake when I posted. You wanted dual primaries and 12v secondary not 6.

My bad. Please accept my apologies!

All the best.

[martin manning]

Is your main PT a dual primay?

No, single with taps for voltage selection.

Too bad. If they were both dual primary then you could switch mains voltage with a DPDT. Maybe your best bet is to use the filament supply.

[Tonegeek]

Is your main PT a dual primay?

No, single with taps for voltage selection.

Too bad. If they were both dual primary then you could switch mains voltage with a DPDT. Maybe your best bet is to use the filament supply.

I might just have to resort to this, which is overkill but would work for my application with some tricks off the 5v tap:

http://triodeelectronics.com/40-18095.html