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Almost ready to connect the socket and SMPS…

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A Sunday morning moment with Fig

Here’s the thing about running 260V through a breadboard;

It’s dangerous! Even I know that, so #1 rule for #1 is no touchy while power on, and FULLY discharge all HV caps prior to going in .

Besides, I get to use the Fig Labs variac! yay. It’s been stinking up my lab for two years so time for it to become useful.

Thanks for reading!

This has been a Sunday morning moment with Fig
 
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While I was monitoring the contest thread last night, and congratulations to @Barry, that’s TWO amps you’ve won (that I know of). (y):love: - I fashioned this little monster…

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I give you the arachnitube . Slick eh? I’ve seen similar pieces for sale, but they were wider and take up too much breadboard. The ”stinger” is the LV heater tap.

Meanwhile I am doing a 30v & 9v version. Much safer working voltages and for those who don’t have a fancy-ass programmable power source perhaps the only route. I’ll grab the 9v schematic CDB posted over at the Boneyard, where you can’t help but learn something, and I recently found this 30v layout which we’ll try first. I’m a little perplexed as to why it doesn’t show the 12v heater tap connection to pins 4 & 8. Crappy schematic? Dumb builder? Both? I have little ego or shame so let’s find out!

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The same rules of engagement should apply as it is a very healthy habit to have, should you later migrate to higher, deadlier voltages.

Stay tuned!
 
Yup…the “stinger” which looks cool as hell is pin 5, not 9 (of course). I’ll throw it in the adapter box and use for a metal can op amp like a hi-rise intake manifold on a hotrod, or something.

So for now, this is the rig..a SIP-style ala stripboard.

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Finished up the Valvecaster, but left out the tone control because I could. Sounds nice @12v (y)

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Now build it into something a bit meatier with a trem or vibe circuit, and yes a tone stage :rolleyes:. We may need some help from an opamp and optocoupler. I’ve got a ton of each so :dmm:

One more detail…..We’re gonna need a bigger breadboard.
 
It was too easy not to feed 9v to #1 filament on one channel and adjust the voltage on the the plates using the other. I cranked it to 30vdc and it does pretty nicely, considering it’s basically a light bulb. I could just up the tolerances on the caps and go for broke (which I will) but I want more than just louder. I also want to have a few tube circuits I can use with my pedal psu, so I’ll get enough juice to them plates using magic, or diodes….maybe magic diodes…charge pump? nah..too many woes.
 
They are handy. Especially if you count to 9 like me. I'd redesign the breadboard bit to only consume a single column. I just hate perfing perf.
 
I should also mention the extreme usefulness when trying out tubes...and in my case a tube tester until mine arrives. I just move the jumper wires around to match the pinout, and adjust the filament voltage to 6 or 12. I'll admit, my swapping prowess is less than 100%..I missed one and happened to see the wattage climbing on the filament channel. I caught it before the ceiling I had set for that channel, but still...eeeeek.
 
Welp, the “tube tester” arrived. It does a pass/fail test on the filament, that’s it. It’s a cool test unit though, an analog multimeter to be precise. Leaks are easy enough to catch, as is red-plating so a test circuit..aka preamp / power amp would be seemingly more useful. I could buy a used amp for this, or build one. I’d like to be able to check / audition as many types as feasible. Circuit suggestions are welcomed. Once I’ve chosen the circuit, I can pick up the required transformers and small parts.
 
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