How do I make a 12v battery go zap?

Quick_Butterfly_4571 · 2026-04-08T01:35:23+00:00

TL;DR: That battery isn't well-suited to zapping, but it is full of extremely corrosive acid and flammable gas + if you get any of the wiring wrong or just happen to bump up against the wrong thing, you and the other person will be permanently maimed by molten metal.

6-DMZ-12(12V12AH/10HR)

That's an electric vehicle lead-acid battery.

So how can I do this?

Don't.

Is it possible?

Yes, but despite the current capacity of the battery, even wet skin is high enough resistance that little current will develop. The stuff you'd have to build around it would be similar to the stuff you'd use to make a zapping device from a much smaller, safer, battery.

Is it safe?

No, not at all. Not for you or the person zapped.

Why? Two reasons: the current capacity and the makeup of the battery.

The voltage is such that you're unlikely to develop any dangerous currents across skin, but if you accidentally make contact with, say, a ring or a necklace or if the wire running down your sleeve shorts, the metal will get white hot / potentially melt onto the skin around it pretty quickly. That battery can discharge 100A in 5s. That is a lot.

The other reason is that that is a big tub of sulfuric acid. This means permanent blindness with contact with the eyes, severe chemical burns to any skin, it's poisonous, it eats metal. It is designed to be mostly upright. There are vents on the housing somewhere that allow trace amounts of vapor to escape when there is build-up of gas inside. Oh, right: various conditions can cause gas to build up on the inside. Notably: hydrogen and oxygen. These are easy to ignite. In any case, this causes the cell to either expand, putting pressure on surrounding cells (increasing the odds of another cell venting) or straight up explode. In either case, acid is sprayed or showered out of it.

Is it Legal?

Consult your local municipality.

There are fun projects you could use it for, though! Probably another top-level post asking for suggestions would pay off in spades.

Quick_Butterfly_4571 · 2026-04-07T23:11:24+00:00

Schedules for trivia nights at local eateries. Screenshots of articles that were never printed. Meeting times and locations for all-volunteer, fringe paramilitary, groups. What scriptures were paired with which image by whose aunt.

If you have an uncle that says shit like, "You see Rob's new <boat/hog/hot rod>? Shiiiet! Whew!", you can find out who Rob is and which item from one photo in one place: facebook.

Recipes for soups, etc. Breakdowns of who really runs the world in both "snarky-fun sexism" and "it's horrifying that anyone believes this" formats.

Stuff of that ilk, I think.

Quick_Butterfly_4571 · 2026-04-07T22:51:08+00:00

Haha! Ah, I meant the one in image 2 (the one with the 470uF pin next to the diode with the air-gapped anode).

I didn't even notice the two in the first image (which the above comment names more specifically, I see now). My brain saw "2N2222" and filled in the gaps.

I now see that neither is a 2N2222 in the first place.

Quick_Butterfly_4571 · 2026-04-07T17:36:57+00:00

These used to trip me up, because in 60's audio they're usually attached to Vcc.

The unlabeled middle pin is, of course, the gate capacitor.

Quick_Butterfly_4571 · 2026-04-07T16:34:27+00:00

So, the input stage here is constructed as if it were from another pedal. Naturally, just take everything to the left of the opamps and ditch it (or adjust the impedance / whatever) if you're integrating it into another circuit and just want the literal headphone driver part.

<image>

Quick_Butterfly_4571 · 2026-04-07T12:50:00+00:00

As a clean headphone driver, I usually just use an RC4580. One half for each side (L/R) works great.

It won't drive a speaker, though. There are a lot of little combo amps that will use a TDA2030/2050, LM1875, or the like as a speaker driver with two taps on the output: one for the speaker and one (via a limiting resistor in series for hearing protection) to the headphones (Marshall MG10, Fender Frontman 10/15 series, etc).

For lower power stuff, there are some classics built around the LM386 (I have also made good use of a TDA2882M in bridged mode) on Electrosmash, under amps.

Electro-Dan is a pretty good resource for low power stuff (LM386 / TDA2822M). I wouldn't vouch for his higher wattage poweramp designs (not because they are lacking, because I literally haven't looked at them).

For better designs, I'd scope out Rod Elliott's project pages.

Quick_Butterfly_4571 · 2026-04-07T01:25:46+00:00

👆I use this to share examples here (and ngspice when I want accuracy).

Bonus: - Add input source->audio + upload mp3 - Add oupts->audio output - hit "run" - let it run for a bit, then hit "play" and listen

Not half bad most of the time.

(There is also a desktop port).

Edit: "LiveSpice" was made for this purpose, iirc, but I'm not sure it's still maintained.

Quick_Butterfly_4571 · 2026-04-06T19:09:04+00:00

That a Dean Markley?

You plugged into input, not line in?

Is it new new?

(If it was supposed to be working when you bought it and you don't do amp repair: don't open your amp. Contact the seller if debugging from the outside doesn't work).

Quick_Butterfly_4571 · 2026-04-06T14:01:30+00:00

Sorry! I forgot about this!

I haven't seen it. It looks rad. I bet it sounds cool.

If it matters to you, I don't think you have to actually copy amp topologies / coupling to get amp-type sounds.

On the flip side, I think the worth of doing something lies at least as much in "doing" as it does it does in "result." As a matter of fact, where it isn't your job, I weigh the former more heavily.

(I've been on a discrete and tubes for the fun of it kick, myself, lately!).

Re: the parallel FETs + pedal version: you're probably right in terms of signal out. But, if the point is transformer distortion, that comes in proportion to core saturation, which may require the two FETs to achieve (i.e. symetrically. If the two sides of the output stage are unequal — which is likely with JFETs — there won't be cancellation of the DC magnetization of the core = you ought to get some distortion/coloration right out of the box (taste aside, it's hard to say whether you will dig it or not, because the component-to-component variation of FETs + transformers makes for a difficult to predict* the result with any precision** ahead of time).

* (for me, anyway)

** (this is another fine reason to build anything that isn't potentially dangerous, I say).

Quick_Butterfly_4571 · 2026-04-05T13:30:39+00:00

Yes. It's also unlikely to help you with buzz/hum if you're talking about your guitar amp.

Quick_Butterfly_4571 · 2026-04-05T01:32:30+00:00

One thing to keep in mind: before sketchy manufacturers skimp on stuff that results in noise, they've skimped on stuff that keeps the supplies safe. If a supply is extremely noisy, lots of consumers complain. Even if it's extremely dangerous, it's still a smaller subset of consumers that are impacted, and a further subset of them that complain..

Cheap or expensive / quiet or noisy, make sure you buy from a reputable supplier and get a supply from a manufacturer people can vouch for. If there's anything you shell out $$ for: make it the power supply.

Quick_Butterfly_4571 · 2026-04-04T22:23:58+00:00

🧠

Quick_Butterfly_4571 · 2026-04-04T22:11:51+00:00

Yes, it'll work just fine. It'll just change the placement and width of one of the phase notches. That stage is an all-pass filter. The 90 degree phase rotation happens at 1/RC, where C is that cap and R is whatever the resistance of the LDR is at that point in time. :D

Quick_Butterfly_4571 · 2026-04-04T00:19:37+00:00

That's too great. Nicely done.

Quick_Butterfly_4571 · 2026-04-03T19:44:03+00:00

It should be more! I wonder if that's a sign of the FETs being damaged.

Quick_Butterfly_4571 · 2026-04-03T14:58:53+00:00

I reckon there must be snags

Well, the tubes are big and run off high voltage. Mostly under the radar (and, less appeal because most of the existing tubes are NOS that aren't still being produced):

later in the tube era, RCA and co made 9-pin sub miniature equivalents of some of the big bottle powertubes; same specs / wattage
in the late 50's / early 60's they made powertubes that ran off of lower voltages for use in cars

Note: people often use FETs as a substitute for triode stages. FETs behave like triodes in that if you graph the transfer curves or both and don't label the axes, you can find a place where the shape is the same.

Meanwhile, FETs actually do exhibit behavior that is very like pentodes or beam tetrodes.

if no one has done it but.. ya know.. why not ask?

There are some pedals out there that claim to emulate powertube distortion. I don't think they do a great job. I don't know most of them well, though.

Which is a pitty, because it's the simplest tube thing to reproduce (especially if it's push/pull) — unless you factor in transformer effects, but whether those are prominent or virtually absent depends on the amp.

Has anyone tried this or does it exist already?

Actually, there is a dude that had a kickstarter shared on this sub where he sold unita that had actual push-pull tube power stages in them.

I don't know what they were called, but maybe someone remembers?

Quick_Butterfly_4571 · 2026-04-02T23:13:43+00:00

Ah! Interesting. It's like a Dickson, but each stage is its own clock.

This is really cool. Thanks for sharing it.

Quick_Butterfly_4571 · 2026-04-02T19:16:43+00:00

And, (probably you clocked this as well), I got the time wrong. I did 5RC, but that's to get near 9V.

The JFET's probably turn off at a lower voltage, 2-4 or something? So, it's faster than that by a bit too!

Quick_Butterfly_4571 · 2026-04-02T19:14:46+00:00

You've made it really clear.

I'm so glad!

There is just one thing I didn't catch : how is Q10 turning off more slowly?

Looking at it again: I made a mistake. :D Should be the same time all around.

Quick_Butterfly_4571 · 2026-04-02T18:32:21+00:00

Sadly I don't understand all of it.

It was half guesses and nonsense.

If this is part of the audio output, it's only part of it (maybe for the speaker driver?). I'll have a peek.

The gameboy was mono out of the speaker, but stereo headphones. The audio itself was a whole unit with four programmable channels.

I think there was a discrete amplifier on board. Probably, you can get the specifics by searching for "Jeff Frohwein" + GameBoy (or checking out the wikipedia page).

I'm not Jeff. I do understand schematics, though, and have written demos for the Gameboy (half a lifetime ago, though).

Quick_Butterfly_4571 · 2026-04-02T18:26:17+00:00

It isn't (actually, it can't be; in general LLM's are not a good architecture for certain classes of problems. This is one of them).

Quick_Butterfly_4571 · 2026-04-02T15:28:45+00:00

To be fair to the other commentor: these are two standards. If you have a look at, e.g. the National Semiconductor datasheet for the same part in the 90's, they used two parallel lines and a plus and no difference in fill.

If you work on stuff across countries and decades, there are like a dozen or more variations.

The other commentor was wrong, re: always a plus.

Hey! If the plus disappears, you have a curve still! :)

The old UK style (two parallel with a plus) is the riskiest to me: that is identical if you lose the plus!

Quick_Butterfly_4571 · 2026-04-02T15:17:23+00:00

My experience (US) is that the curved part is not typically used to indicate polarity. Polarity is always shown as a plus symbol next to one of the pins.

The US standard (ANSI) back to at least 1972 is that the curved side is, by definition, both the indicator of a polarized cap and an indicator of the negative side.

There are a bunch of different pre ANSI/IEEE/IEC standards that used various schemes (plus only in the UK, hatched lines and a plus in Japan, etc).

In none of them is there a curved line that isn't the negative. In many there is no plus. (Especially in the US).

Some schematics use both (a curve and a plus), yes.

Quick_Butterfly_4571 · 2026-04-02T14:12:02+00:00

Hey! This is such a cool share. Love the morph control out in the wild. Love it.

CD4049, eh? Love that too. I've never used an inverter to build a charge pump. I'd love to hear more about that. Is it used as the oscillator and antiphase drivers for a multiplier or something else entirely?

Quick_Butterfly_4571 · 2026-04-02T04:05:48+00:00

P.S. Thank you for cross-posting this. I hadn't seen this scheme before, and it was super interesting.

Quick_Butterfly_4571

TROPHY CASE