LED instead of Lamp wiring

[chunkitup]

I have a stripped out PV Butcher that will be host to a cloned amp. I dont want to drill a hole for a lamp and jewel and instead use the existing two holes that house the power and status led's. I have 2 radio shack led's with built in resistors. The forward voltage for the led's is 12v typical and 16vmax.

Would someone be so kind to help me design the circuit that will utilize these led's?

[chunkitup]

Should I just use a voltage divider off the secondary to get 12v and not worry about the status led to keep things simple. Or should I work with the heater taps?

[jmaf]

Should I just use a voltage divider off the secondary to get 12v and not worry about the status led to keep things simple. Or should I work with the heater taps?

Hi, for most LEDs you can just take power from the 6.3V heating line in series with a 470R resistor to one of the LED terminals.

For a 12V heater line you can a use 1k resistor in series with the LED.

What's your question about the status LED? Should be pretty simple as well.

[chunkitup]

How can I have the status led illuminate when the stand by is switched? Also, should I rectify the heater voltage?

[Enzo]

You can just replicate the little status light circuit that was there originally. A small transistor and a coulpe resistors.

[jmaf]

How can I have the status led illuminate when the stand by is switched?

Use a DPDT standby switch, on one pole you interrupt the HT supply(standby), on the other pole you feed LT voltage to a LED

Also, should I rectify the heater voltage?

To feed the LED, you probably don't need to rectify. Your eyes can't see the 60Hz pulses, the LED will just turn on during the positive cycles. Of course if you want, there's no poblem, any single 4001 diode will do, half wave rectifier(current here is 5 to 6 mA).

Unless you're asking about rectifying the heater circuit completely including the heaters, that's a different question altogether. In short yes you can but you probably should not add filtering caps or voltage will surge up to 40% and will ruin your filaments.

[chunkitup]

Thanks for all the good info guys. I will probably replicate the status led circuit that was originally in there.

[chunkitup]

New Idea

OK here is the scheme and what I was thinking I could do was keep the same circuit as the butcher but instead of using that circuit for the bias I could use it for elevating the heater ground. Do you think that this is a viable idea?

[chunkitup]

Please review new circuit

Alright here is a scheme of what I want to do. The orange sec taps will be used for the bias and led's. Could someone look over and let me know of any mistakes there may be? Is this circuit as simple as it could be?

[jmaf]

Alright here is a scheme of what I want to do. The orange sec taps will be used for the bias and led's. Could someone look over and let me know of any mistakes there may be? Is this circuit as simple as it could be?

Hi chunkitup, correct me if I'm wrong, you're obtaining this power from the bias circuit (O coil)? The schematic says -55V here...

I'm not familiar with the Butcher amp but I think you meant the heater circuit (Y coil), judging by the cap values and resistors you chose.

Even if you meant the heater circuit, the two circuits seem mixed here. There is a BIAS label on your drawing but you can definitely not obtain your BIAS voltage from there or you'll fry the 6L6 within seconds of turning it on(a positive BIAS will be tube chernobyl).

[chunkitup]

Missing Diodes

Ok here is the circuit straight out of my PV Ultra 60. You were quite correect about blasting the 6L6's with that positive voltage, whoops!! Do you see any problems with this circuit.

[jmaf]

Ok here is the circuit straight out of my PV Ultra 60. You were quite correect about blasting the 6L6's with that positive voltage, whoops!! Do you see any problems with this circuit.

Yes there are problems, for starters you'll get 0v BIAS with that one.

I can't draw a suggestion for you here at work, but in principle I think you should separate the BIAS and your status circuits in two.

The LED circuit should go on the Y windings, fed at most 12V.

The BIAS circuit goes on the O windings to provide the adjustable -55V.