This Week on the Breadboard: A Mini Tube Pedal

6418 tubes were originally designed to be used in portable, low-power (2mW) amplifiers. Tube part numbers that consist of four digits are hi-rel, ruggedized tubes for military applications. The datasheet is dated July 1, 1963. The date code on the box is Dec 1978.

I think it sounds great. Smooth transition from clean to mild distortion to fairly crunchy as one turns the GAIN up.

A have a few other ideas for using these in pedal circuits.

Turns out that bypassing the filaments to ground is unnecessary because the AC resistance between filament and ground is only a hundred ohms or so.
 
The directly-heated cathode limits the circuit choices. A cathode follower requires an isolated filament supply. Basically, the cathodes (filaments) need to be at, or near ground.
 
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Sounds great! I raised C1 to 10nF. It made quite a difference. I may try something between to mellow it a bit. (y)

Edit: (yes Fig, explain how you loved it so much you immediately changed it) :ROFLMAO:
 
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Waking up an old thread...

I have *dozens* of these 6418 tubes...

These tubes were used in *hearing aids*, among other uses.

The microphonics are legendary, thump the board and it'll ring for twenty seconds.

Ive used them in usb headphone preamps, and theres a pair warming up my entertainment center audio. I've also made an overdrive circuit, but that never tolerated a footswitch so it's an always on effect.
 
Could this work if I utilized a MAX1044 or TC1044SCPA charge pump instead of your TC7762B or bench supply, pinouts aside?
 
Revisiting the Fender, I ran it straight into a SS power amp and it really shines. I have a Hartke Kickback 12 enclosure I gutted and put a Jensen Special for the time being, but I'd like to maybe get a Celestion Blue in there as the cab is pretty tight. The head slot is begging for this kind of setup, and I've got several power amp chips around I can build around, so thanks again...more fun! (y)
 
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