183 build questions

[professormudd]

I was wondering: Can I run the power LED off of the relay supply since it is right there? I am hoping I can just connect the LED to terminal strip where I have the voltage regulator connected.

My apologies if this is a stupid question (my post history is surely riddled with stupid questions)

[pompeiisneaks]

No reason you couldn't, you'll just need to adjust the dropper for the voltage on the LED so you don't burn it up. (i.e. if it was going to be used on 6.3VAC and now is going to be used on 12VDC you need to ensure the led dropper is right). Tons of online clacs, but basically: http://ledcalc.com/

is one of many. You need to know what current the LED can handle w/o burning up, the voltage drop over the LED and the supply voltage and you can get the right dropper resistor. You can just overdo it but then you may get a dimmer LED...

~Phil

[professormudd]

No reason you couldn't, you'll just need to adjust the dropper for the voltage on the LED so you don't burn it up. (i.e. if it was going to be used on 6.3VAC and now is going to be used on 12VDC you need to ensure the led dropper is right). Tons of online clacs, but basically: http://ledcalc.com/

is one of many. You need to know what current the LED can handle w/o burning up, the voltage drop over the LED and the supply voltage and you can get the right dropper resistor. You can just overdo it but then you may get a dimmer LED...

~Phil

Thanks.

I am planning on powering the relay supply with 6V, so I believe I can still use the same dropper, but I no longer require the diode, correct?

[xtian]

but I no longer require the diode, correct?

No, the LED is, itself, a diode. In some cases, an extra diode will help, because it drops half a volt. But 6v is no problem for an LED.

[martin manning]

I was wondering: Can I run the power LED off of the relay supply since it is right there? I am hoping I can just connect the LED to terminal strip where I have the voltage regulator connected.

Sure, no problem, but you need a current limiting resistor somewhere.

I am planning on powering the relay supply with 6V, so I believe I can still use the same dropper, but I no longer require the diode, correct?

Correct, and you can eliminate the whole terminal strip assembly next to the power tube sockets. Your relay supply board has a full-wave bridge rectifier (four diodes and two caps). There are two current limiting resistors on that board, and you can use one of them for the panel LED. Is the 6V mentioned above the AC voltage are you feeding in? What regulated DC voltage you are expecting to get out?

[professormudd]

Yes, 6VAC into the rectifier. I'm not sure what DC voltage value to expect out.

[martin manning]

You can get 5VDC out, but you will need a low dropout regulator. Where is that 6VAC coming from?

[professormudd]

A Hammond 166F12B power transformer. It's 12VCT.

[martin manning]

If you are using 12VDC relays you will need to put the whole 12VAC in.

[professormudd]

If you are using 12VDC relays you will need to put the whole 12VAC in.

I am using 12V relays. Omron G5V-2-H1-DC12.

I assumed that was a maximum, because I used them on my previous 124 build and supplied 6.3VAC via a Hammond 186B12 and it functions correctly (at least I believe it does).

[martin manning]

If you are using 12VDC relays you will need to put the whole 12VAC in.

I am using 12V relays. Omron G5V-2-H1-DC12.

I assumed that was a maximum, because I used them on my previous 124 build and supplied 6.3VAC via a Hammond 186B12 and it functions correctly (at least I believe it does).

The 124 relay supply (as drawn) has a voltage doubler rectifier, so it operates on 6.3VAC. You have 12VAC available here, so no worries.

[professormudd]

If you are using 12VDC relays you will need to put the whole 12VAC in.

I am using 12V relays. Omron G5V-2-H1-DC12.

I assumed that was a maximum, because I used them on my previous 124 build and supplied 6.3VAC via a Hammond 186B12 and it functions correctly (at least I believe it does).

The 124 relay supply (as drawn) has a voltage doubler rectifier, so it operates on 6.3VAC. You have 12VAC available here, so no worries.

Thanks. I am certainly glad to have learned that here before I started soldering. Should I ground the CT on the little power transformer?

[martin manning]

Should I ground the CT on the little power transformer?

No, leave it unconnected and insulate the end of the lead with heat shrink.

[professormudd]

Thank you. I appreciate all of the advice.

[professormudd]

Did a bit of work last couple days. Next I'll start wiring in the preamp board.