You likely need a plate power supply of at least 100V for the tubes to operate.
If you accidentally touch that, you will remember it for a long time.

A “long time”, I assume, means “the rest of your life” - anywhere from 90+ years to a few tenths of a second.

 

You seem to have a good variety of dissimilar triodes - one power triode and one small signal triode. They were for the vertical deflection output of a television and the amplifier to drive it
Most of the television "deflection output" devices will make good audio power valves, so you could make yourself a headphone amplifier or small audio amplifiers - but you would have to buy the output transformers and they're not cheap.

 

You seem to have a good variety of dissimilar triodes - one power triode and one small signal triode. They were for the vertical deflection output of a television and the amplifier to drive it
Most of the television "deflection output" devices will make good audio power valves, so you could make yourself a headphone amplifier or small audio amplifiers - but you would have to buy the output transformers and they're not cheap.

I have many more tubes. I have two boxes with around 100 tubes each. I just listed the ones with triodes for the circuit I intend to build. If this works out, I might move on to other projects like the ones you mention. I'm usually more interested in digital electronics than analog (let alone vacuum tubes!), but since I already have the tubes, and this looked like a fairly simple project, I decided to give it a try. I checked the price of new tubes on hificollective, and if I didn´t have the tubes and I had to buy them I probably wouldn't.

 

You can new old stock valves for US$0.75 each!
https://vacuumtubes.net/Quantity Specials/Quantity specials.htm
But if you want a matched pair of brand new EL34s to make your guitar sound just right, they might be rather more expensive than that.
By they way - I just looked and they do sockets as well
https://vacuumtubes.net/Prices Relays, etc.htm US$2 each. Scroll down a long way (it's not a flashy website) to PCP7 and PCP9

 

I have received the sockets, and I'm now ready to put the circuit together. I'll use either two 6FH5 triodes or two 6DZ4 triodes. This are the tubes pinouts and the circuit using two 6FH5:

I'm using a DC30V/400mA power adapter. RL1 and RL2 are the current limiting resistors for the LEDs. The capacitors are 4u7uF/63V and the resistors are 560K (I missed the K in the schematic). The LEDs will go on and off every ~2sec (0.69x0.0047x560,000=1816ms). My questions:

1) Are pins 3 and 4 (the heater) interchangeable? I will power the heater with two 3V coin batteries, but does polarity matter?

2) Does pin 7 of either tube go connected to anything or I just leave it floating?

3) If I want to use the 6DZ4 tubes... I think I have to swap 5 and 1 and leave everything else the same? Do I need to connect pins 6 and 7 to anywhere?

4) If I want to use bulbs instead of LEDs, do I just replace the LEDs and the current limiting resistors with the bulb? Do I need a resistor?

5) Is there anything else I'm missing?

Thanks a lot for your help!

 

I will power the heater with two 3V coin batteries,

That won't last long, each 6FH5 tube draws 200 ma at 6.3 volts. The 6ZD4 draws 225 ma.
Polarity is not an issue.

 

That won't last long, each 6FH5 tube draws 200 ma at 6.3 volts. The 6ZD4 draws 225 ma.
Polarity is not an issue.

Perhaps I can make a voltage divider to get 6V from 30V? The circuit is a proof of concept anyway, and it's not intended to be powered for long periods.

 

Perhaps I can make a voltage divider to get 6V from 30V?

You still need 400 ma to operate the heaters. I would operate the heaters from a USB 5 volt charger that is good for 1amp or more. Where did you get those values for R1 and R2? Do you realize how fast the time constant is? Did you mean 560K?

 

You still need 400 ma to operate the heaters. I would operate the heaters from a USB 5 volt charger that is good for 1amp or more. Where did you get those values for R1 and R2? Do you realize how fast the time constant is? Did you mean 560K?

I did 0.69xRxC = 0.69x560x4.7 = 1800ms

 

OK. I misread the value for C1 and C2.
You have 4.7 Farad capacitors?
I think 560K resistors and 4.7uf caps would be more practical.

 

OK. I misread the value for C1 and C2.
You have 4.7 Farad capacitors?
I think 560K resistors and 4.7uf caps would be more practical.

No, no. You were right. I messed up. I said 560 ohm and 4.7uF, which, as you said, is too fast. What I REALLY meant to say is what you said first: 560K and 4.7uF. Sorry.

0.69x0.0047x560,000=1,800ms

 

What I REALLY meant to say is what you said first: 560K and 4.7uF.

OK. That sounds a lot better. Have you decided on how to power the heaters?

 

OK. That sounds a lot better. Have you decided on how to power the heaters?

In the meantime, I'll just do what you suggested: two power adapters (30V and 5V). Maybe I'll think of a "cleaner" solution later.

 

I'll just do what you suggested: two power adapters.

Only one adaptor is needed, you can parallel the heater circuits.
Anyway let us know how it goes.

 

Only one adaptor is needed, you can parallel the heater circuits.
Anyway let us know how it goes.

I mean, one adapter for the two heaters (5V) and one adapter for the rest of the circuit (30V).

 

Alternatively, you can put the heaters in series, which gives 12V at a lower current.

 

Alternatively, you can put the heaters in series, which gives 12V at a lower current.

Then, would I be able to get the 12V from the 30V with a voltage divider without the current suffering as much?

 

12V @ 200mA or 225mA. You'd still need a 5W resistor (90 ohms or 80 ohms) but if this is just an experiment, then it's not so important.
To get 6V @ 400mA or 450mA it would bt 10W.

According to the datasheet, you'll get a lot more current out of the 6DZ4 than the 6FH5. The 6FH5 will give you about 3mA maximum, with the anode at 30V, but you need the anode to get lower than that to discharge the capacitors.
The value called "Plate resistance" is approximately equivalent to Rds(on) for a MOSFET, and at 5.6k it's an awful lot more than you would be used to for MOSFETs!

 

It would probably work better with RL1 = RL2 =22k.
The LEDs will be dimmer at about 1mA but would still be easily visible.

 

The 6FH5 will give you about 3mA maximum, with the anode at 30V,

That spec was with a grid voltage of 0 volts. At initial startup the grids would be almost at supply. One would think the current would be higher and the plate resistance lower.
The 5600 plate resistance number you mentioned was with a grid voltage of -1volt in a class A amp configuration.