Relay power supply transformer

[blue_dog]

Hi,

newbie, question. Is there a layout that indicates clearly how to wire the relay power supply transformer? most layout's I've seen have a tap from the power supply, am I correct? can someone send me a link?

What type of transformer can I use for this? I've seen ones from radio shack, etc...

[Structo]

I think that most guys making a Dumble clone use the 5v taps off the PT.
They are usually yellow.

[Funkalicousgroove]

alot of Real dumbles use a 12v 450mA radio shack transformer, My transformers have an extra 6.3v tap to run the relays. You can use the 5v rectifier tap if your PT has one.

What are you building?

['67_Plexi]

alot of Real dumbles use a 12v 450mA radio shack transformer, My transformers have an extra 6.3v tap to run the relays. You can use the 5v rectifier tap if your PT has one.

What are you building?

Hammond 186C12 is a good transformer if you are building an amp to work on Continental voltages to. The Rad Shack only has a 120V primary.

You could also do as Gary does and spec a transformer with an extra tap.
Save yourself the trouble and don't try to use the same supply as the filaments. Some people on here say they have done it effectively. But I question their acceptable noise floor limits.
Definately recommend decent filtering and regulation. The relay supply can induce noise in the preamp stages unless you spend the time to filter and regulate it properly.

[blue_dog]

Hammond 186C12 is a good transformer if you are building an amp to work on Continental voltages to. The Rad Shack only has a 120V primary.

You could also do as Gary does and spec a transformer with an extra tap.
Save yourself the trouble and don't try to use the same supply as the filaments. Some people on here say they have done it effectively. But I question their acceptable noise floor limits.
Definately recommend decent filtering and regulation. The relay supply can induce noise in the preamp stages unless you spend the time to filter and regulate it properly.

thanks, you answered my next question. I'm working with a 022814 clone, the domestic 120V, I was suspecting of wiring it to the filaments but wasn't sure.

Can you correct if I'm wrong, The relay supply transformer primary wires would be connected to the fuse and main switch (just like how the power transformer is connected)? If not, what would be the best location to solder it?

['67_Plexi]

Hammond 186C12 is a good transformer if you are building an amp to work on Continental voltages to. The Rad Shack only has a 120V primary.

You could also do as Gary does and spec a transformer with an extra tap.
Save yourself the trouble and don't try to use the same supply as the filaments. Some people on here say they have done it effectively. But I question their acceptable noise floor limits.
Definately recommend decent filtering and regulation. The relay supply can induce noise in the preamp stages unless you spend the time to filter and regulate it properly.

thanks, you answered my next question. I'm working with a 022814 clone, the domestic 120V, I was suspecting of wiring it to the filaments but wasn't sure.

Can you correct if I'm wrong, The relay supply transformer primary wires would be connected to the fuse and main switch (just like how the power transformer is connected)? If not, what would be the best location to solder it?

Mains comes in. The incoming neutral connects to one of the primary wires on both transformers. The incoming live goes to the mains fuse first (use the connection on the end of the fuse, this avoids potentially touching a conductor if you replace the fuse with the amp still plugged in the wall). From the 'side connection' of the mains fuse go to the power switch, from the power switch connect to the other primary wire on both transformers. The 186C12 has solder terminals on it that makes joining the primaries real easy.

[blue_dog]

alot of Real dumbles use a 12v 450mA radio shack transformer, My transformers have an extra 6.3v tap to run the relays. You can use the 5v rectifier tap if your PT has one.

What are you building?

I'm trying to build a ODS 50w amp. Unfortunately I have access to a 022822 clone PT, so I don't have any extra taps. Is it a 6, 12, or 24vac secondary? does it make any difference because of the 7812 voltage regulator?

[ic-racer]

I'm using the Xicon Heavy Duty Power Transformers TRANS FIL 6.3V 1A from Mouser.com

It goes to a voltage doubler and then to the 12v regulator.

I have it wired to the mains per #124 as follows:

[benoit]

I'm using the Xicon Heavy Duty Power Transformers TRANS FIL 6.3V 1A from Mouser.com

It goes to a voltage doubler and then to the 12v regulator.

I have it wired to the mains per #124 as follows:

What does the ground switch do in that circuit?

[heisthl]

SHocks the crap out of you if you put it in the wrong position
Seriously in the days of 2 prong power it let you switch which power wire was ground from the chassis point of view. (ever get shocked when your lips touched the mic? flip the ground switch) In our modern 3 prong world it is not needed and potentially dangerous (that's why some call it the death cap). If you are really concerned about bad power at a nightclub and don't want to carry an outlet checker you can put the mains fuse in your amp on the "neutral" side (white wire) and hardwire a cap (.047 or .068 are good values) between earth ground (the green wire you ground to the chassis) and the other side of the fuse. If the outlet is wired wrong you will just blow a fuse and not hurt anything.

[Guitarman18]

Funk wrote:
[My transformers have an extra 6.3v tap to run the relays. You can use the 5v rectifier tap if your PT has one.
]

Funk, do you feel that having 6.3v gives you an advantage over 5v? Less chance of voltage dropping too low?

[FUCHSAUDIO]

If you use enough filtering, 5.0 volts doubles to 10 and you regulate to 6.0 volts. You can use 6.0 volts and have an extra margin for low line voltage or to prevent regulator drop-outs (although you can buy regulators with low dropout capbility). If you use an aluminum chassis you can use it as a"free" heatsink.

BTW: If you have a 5.0 volt filament winding on your existing transformer, you would have enough current for one or two preamp tube filaments to be run on DC .

[ic-racer]

I'm using the Xicon Heavy Duty Power Transformers TRANS FIL 6.3V 1A from Mouser.com

It goes to a voltage doubler and then to the 12v regulator.

I have it wired to the mains per #124 as follows:

What does the ground switch do in that circuit?

The user can filp the switch around to try and eliminate hum, if present. Looks like HAD just copied it from Fender.

IF (big IF) you are plugged into a correctly wired, grounded outet in the USA, a shorted cap will cause no harm. In one position a shorted cap does nothing because ground and white are connected together in the circuit breaker box of a correctly wired building anyway. In the middle position, a shorted cap, of course does nothing. In the other position a shorted cap should will blow the circuit breaker in a correctly wired building when the device is turned on.

IF you are plugged into an INCORRECTLY wired outlet and the cap is shorted....well check out this thread https://tubeamparchive.com/viewtopic.php?t=4543

Everyone has an opinion on these, and mine is that my safety is best served by ensuring my home studio is wired correctly with appropriate breakers and GFIs and grounding.

If I played out in uncertain electrical territory, I would want to keep the switch in the middle position. However, since the switch could easily get bumped, removing that cap could be a safety feature.

[Pete]

I have a couple amps I'm using the 12v @ 450mA Radio Shack in, with a 7812. I suspect this isn't the best way to go for two 12V relays but I have never had a problem/failure in going on 8 years (wow, has it really been that long, time flies when you're having fun).

alot of Real dumbles use a 12v 450mA radio shack transformer, My transformers have an extra 6.3v tap to run the relays. You can use the 5v rectifier tap if your PT has one.

What are you building?

I'm trying to build a ODS 50w amp. Unfortunately I have access to a 022822 clone PT, so I don't have any extra taps. Is it a 6, 12, or 24vac secondary? does it make any difference because of the 7812 voltage regulator?

[FUCHSAUDIO]

During our CE certification process I learned NO country requires nor sanctions a "ground switch" anywhere.... With a three prong cord, it should not be required. With a two prong (in countries where they have such things) it can make things quieter, but is not an accepted item to have. In Japan, I know my distributor mentioned that they often run a wire from the chassis to ground to fix noise issues. We deleted it on all models a year or two ago. In the current Fender repros (65 Twin reissue etc) the switches are installed, but not wired.