Just put 6L6's in my D'Lite

[BobW]

Using the 1.2A Radio Shack 12.6V xfmr and a regular bridge rectifier topology I can power 3 12V relays simultaneously and the regulated voltage stays locked at 11.94V (7812 regulated). I have to wait to get the 5-pin XLR cable to test the 3 LEDs also.

If you have the same xfmr there is no reason to use the doubler, IMHO.

That doesn't make sense. My circuit only requires 2 relays and 2 LEDs, so why would I or anyone else purchase an extra transformer and regulator if a simpler voltage doubler works? Also a relay doesn't need a regulated DC voltage to operate; only a window between minimum coil pickup voltage and maximum. Anything else in between is sufficient for relay action.

This same voltage doubler circuit has worked well in a Bassman REV A clone for about 1 1/2 years, and through more than 60 gigs. So I'd say any infant mortality about circuit reliabilty is out the window.

Also it's fewer parts count (2 diodes, 3 caps, 1 resistor) vs (1 transformer, 4 diodes or bridge, 2 caps, 1 regulator) Additionally, if you go the Vregulator route, make sure you also install a diode from Output to Input at the regulator. This prevents the output from exceeding the input during turn off, and if omitted, can sometimes damage the Vregulator. (See 7800 series data sheets).

Finally, additional voltage doubler circuits or a voltage tripler used for more relay switching would be more cost effective than a transformer/Vreg approach. hth my $.02

[mat]

Has anyone tried a combination of a 6L6 and an EL34?
My amp has a dual bias circuit so i might as well use it.
Will let you know...

Ed

Have You tried this yet ? Is it possible to combine 6L6 and EL34 in a same amp ?

[brownnote]

I haven't tried it but it's certainly possible.

[BobW]

Ed de Jager wrote:
Has anyone tried a combination of a 6L6 and an EL34?
My amp has a dual bias circuit so i might as well use it.
Will let you know...

Ed


Have You tried this yet ? Is it possible to combine 6L6 and EL34 in a same amp ?

I was planning on trying EL34's in place of the 6L6s tonight, but a combo of the two does sound interesting. Even though both tubes could bias at the same idle current, the top and bottom of the waves will be different, if it's for the better, I don't know yet. I'll give it a try and scope it out later in the week.

I completed the voltage doubler, relays, and footswitch circuits last week. No problems during the Sat. night gig, but the LEDs could probably use a little more current limiting (<20mA), and were too bright on a dim stage.

[heisthl]

I've done some experimenting recently with footswitch leds - The simplest setup is to use a 1k to 2k7 and the led in series across the footswitch terminals for a light when the circuit is open (like for a reverb foorswitch), and for the typical boost/overdrive switch where you want a light on when the circuit is closed use a 47 to 270 ohm in parallel with the LED and put that pair in series with the switch. In either case you can play with r values for brightness levels.
If you want panel indicators for the boost/od style you can just wire the LEDs across the relay protection diodes. For the reverse (like a Reverb on indicator) use the anode side of the Reverb relay protection diode as the Vcc and give the LED a ground path through a 1k to 2k7 (adjust for brightness).

[BobW]

I've done some experimenting recently with footswitch leds - The simplest setup is to use a 1k to 2k7 and the led in series across the footswitch terminals for a light when the circuit is open...

I like just the opposite, PAB and OD ON = LED ON.

It just a matter of using this simple formula:

LED current = (Vs - Vf) / Rs

where:
Vs = source voltage
Vf = LED forward voltage drop ~ 2v for red, 3v for white. blue
(check data sheets for your particular led)
Rs = series resistor

If using a voltage doubler circuit, your souce voltage will sag depending on the number of relays and LEDs used. This is OK, as long as the source voltage is still greater than the minimum coil pickup voltage (see relay data sheet). The voltage sag also results a slight difference in LED current, but the visible difference is minimal.

[heisthl]

I like just the opposite, PAB and OD ON = LED ON.

Reread the above post

It just a matter of using this simple formula:

LED current = (Vs - Vf) / Rs

where:
Vs = source voltage
Vf = LED forward voltage drop ~ 2v for red, 3v for white. blue
(check data sheets for your particular led)
Rs = series resistor

All good, but one point of my post was to NOT use a series resistor/LED string for the "closed circuit" LED. By using the LED in parallel with a resistor you improve the reliability of the circuit. You could use regular diodes in parallel instead of a resistor but the resistor allows you to adjust brightness levels. [/quote]

[BobW]

By using the LED in parallel with a resistor you improve the reliability of the circuit.

Not true. Reliability is out the window anyway since the relay contacts are more likely to fail w/ lower MTBF, (mean time between failure) compared to an unstressed resistor or LED, in parallel or series.

All good, but one point of my post was to NOT use a series resistor/LED string for the "closed circuit" LED.

We're implementing different designs here, it's just a matter of taste. I like my circiut, you like yours. I doubt either of us will change our designs or our minds.

[heisthl]

My way drops less voltage na na na na na

[BobW]

LOL!

So how do you like your RD-50 coverted clone? Are you happy with the speaker choice?

[stelligan]

Love the RD50 clone. heisthl built that for me. After some PAB tweaks it's done. Now has an EV12L and sounding damn fine. I will post some newer clips soon on it's thread. I've just been lurking on this thread and giggling at how this thread about 6L6's in a D'Lite turned into friendly debate regarding powering LEDs in foot switches. I need to get out the soldering iron and get me some lights. Which method should I implement?? I can set up an Indian leg wrasslin' match

[mlp-mx6]

Well, I'll stick my neck out. Here's what I have done.

I found 12V LEDs at Radio Shack that have a built-in resistor. (They're nearly flat to the surface also, which I consider a plus for a footswitch application.) All I had to do was provide 12V across the LED wires with the proper polarity.

I use a 5-pin XLR to connect the amp to the footswitch. The 5 wires are -

+12V
Ground
OD Relay
PAB Relay
Mid boost relay

I use a DPDT for each of the 3 switches. One side switches the relays to ground. The other switches the +12V to the positive side of the LEDs.

3 switches, 3 different color LEDs. Works great.

[BobW]

Which method should I implement?? I can set up an Indian leg wrasslin' match

LOL!

The choice is your's my friend.

My apologies to all for sniping the post. Heisthl and I were just having a meeting of the minds. I love this site! It has always been a great place for learning, sharing and discussing ideas.

[heisthl]

SPST switches are cheaper and you don't need a supply wire in the footwitch. Stelligan just take your existing footwich and put a 100ohm/LED parallel pair in series with either lead wire. The long lead on a LED is the anode and goes in the non grounded direction.

[stelligan]

Thanks! Spoken in terms that you know a novice hacker like me can understand. Bye Bye Battery