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WIGGLING 'LITE' IN GUEST MODE

Flea Market Find: Analog Exerciser
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Flea Market Find: Analog Exerciser
JenniferG
Found this at the Flea Market. The guy wanted $3 and I couldn't pass up the deal.

I don't know much about it, but figured I'd post a photo of it here because it has a breadboard, knobs and appears to be a tone generator or something.

I see someone selling this piece along with a "Digital Exerciser" for $150.

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Wonder what this unit was used for and if it would be beneficial to a newb synth electronics DIYer like myself. Also wondering how much it is really worth.
Joe.
It looks SUPER dangerous, being mains powered.

Can we see inside please This is fun!

The first thing I'd do is retrofit it with new circuits (CGS etc) and then power it with a wallwart. You could also just remove the Mains, and then power the old circuits with something new, but I wouldn't trust them. If it's broken the time spent fault-finding would better be spent building a new core on a verobaord.

It looks like a platform to test passive filter circuits and op-amp circuits. These were probably a 1st year project at trade school, for Electronic Technicians (I did something similar, but in a plastic toolbox).

I'd be happy to send you a small power +/-12v kit that could power it, if you want to start rebuilding it.





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MrsWedge
"Super dangerous"?

Hardly. Mains are not dangerous if you treat it with some care and respect.
Joe.
MrsWedge wrote:
"Super dangerous"?

Hardly. Mains are not dangerous if you treat it with some care and respect.

I would NEVER plug in some random mains powered equipment i find at a fleamarket, particularly if it looks DIY.

If there's no strain relief on the cord, there's the possibility that its become loose and there's mains floating around in the chassis.

There's a high chance that was assembled by a 1st year student, and it's age is unknown (corrosion?, dry caps? dielectric breakdown of caps?).

Pics of inside please? It's peanut butter jelly time!


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Dcramer
twisted testin’ it in the bathtub or GTFO! lol
appliancide
It's a function generator that was most likely built by a student to use in an analog electronics class. We built more elaborate versions at my tech school, but same basic idea.

The function generator is probably made from a 2206 or 8038 chip.

It's not worth a lot more than you paid for it, but it can certainly be useful. Even if it doesn't work, you can get some good parts from it. Do you have a multimeter or oscilloscope that you can test it with? I wouldn't be afraid to turn it on. Just use a power strip so you can quickly kill power if it starts to smoke.

If it does work, I would recommend peeling that breadboard off and tossing it. The contacts wear out over time, and new ones are not that expensive.
JohnLRice
FYI there is one of those along with its digital counterpart on eBay for $150 cool
https://www.ebay.com/itm/Vintage-Digital-Analog-Exerciser-National-Ins titute-of-Technology-Electronics-/263372866778

I was trying to find an internal picture but no luck.
JenniferG
JenniferG
JenniferG
The voltage regulators are:
7312 & 7912
JenniferG
appliancide
And you thought there was no strain relief Joe. hihi

With +/-12v you could experiment with some basic synth circuits, but I wouldn't expect those outputs to be very clean or robust.

Throw a quarter inch jack on there and use it for drones.
AndyHornBlower
A 7312 appears to be an op amp, judging from a quick google for a datasheet, JenniferG.

So does it only have +12V? You could still make some single rail CMOS circuits on it, if so - like the hex inverter oscillators (usually done with gates with a Schmitt trigger input).

I'm loving the knot in the mains lead smile

I'd be tempted to at least take the transformer out, and house it separately, partly because that does look quite dodgy, but also because it will reduce the hum. I have some powered speakers, which claim to be budget monitors, which hum for that reason.

I took the transformer and voltage regulator out of a set of powered PC speakers that broke, and fitted a socket to take an external wall wart. That made them much quieter.

FWIW, I'm temporarily running my Doepfer modules on two 3xAA cell battery clips, with 4.1V Li-Ion 14500 (AA sized) batteries. It doesn't run for very long on them, but it's nice and quiet. The trick is to connect the two clips in series, and take ground from where they join. It's very close to +/-12V, very portable and probably a lot safer.

Something you're likely to build on that breadboard could run for quite a while on batteries.

Most guitar pedal stuff runs on +9V with a virtual ground at 4.5V (made internally, often just with two resistors), so +/-5V to 6V is plenty for most op amp or transistor based circuits - i.e. you could just use 3 or 4xAA NiMH cells for each power rail, in clips.
Joe.
That single sided circuit board, with no solder mask, is going to make it really easy to trouble shoot if there's something wrong. Great find thumbs up





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KSS
This Analog Exerciser sounds and looks familiar. Probably someone like Don Lancaster wrote an article in Popular Electronics.

Don't know whether to feel old or just smile when these older projects appear and the omigod A/C scare reactions show up. Joe's comment about not plugging in an old A/C driven project without first doing some basic investigation is sound and safe advice.

It would be nice if everyone could have experienced the time when Heathkit, EICO, PAIA and so many others offered kits intended for raw beginners with assembly and instructions where A/C was openly possible to be touched during building and testing. People built tube televisions. AC powered oscilloscopes, VTVM,s. I can't remember ever hearing or reading of anyone being electrocuted by a home made device like this. Shocked? Yes, been there myself. But never seriously hurt through many A/C Mains powered DIY projects in my youth and since.

In all the hundreds of A/C powered PAIA kits with similar construction to this analog exerciser out there, has anyone ever heard of anyone being killed or seriously hurt by one? My goodness, to think I walked alone or with friends and sometimes rode a bike to school until college. The horor.

Reasonable caution towards A/C mains is advisable and smart. Fright and scare tactics less so.
AndyHornBlower
I've been shocked by UK mains, more than once, when I was younger, which was 240V 50Hz, at the time... Now officially 220V +/- 10%, which tends to still come to 240V.

I survived, but then I was in my twenties. A while later, I had to have an ECG, which showed an arrhythmia - my heart was beating in roughly 5-4 time. Maybe it still is; I'm not sure.

A friend of mine was less lucky. He got his thumb caught as he got electrocuted, and had a hole burnt clear through it. I visited him in hospital - you could see daylight through it. He was in his twenties too. I wouldn't fancy our chances if we did the same thing now.

US mains voltage is a lot more sensible, of course. I still wouldn't want to take risks with it.

Sure, I'd work on things that are AC powered, and do, but if it was something I picked up second hand, evidently hand made by an an amateur, and not certified safe by anyone (as it would have to be, if it was from a charity shop in the UK)...

I'd strip it out and start again.

Plus, there's the hum. Building audio circuits on top of a transformer is not a good start, unless you want to build a mains frequency drone, for some reason.
SoundPool
I tend to avoid mains power projects because I don't want to mess with something I don't fully understand, but from what I gather part of the caution towards it on this board in general has to do with the amps and that messing around with a big toroid transformer on something like a larger modular case is even more dangerous than your typical already unpleasant to dangerous or lethal zap.

My grandfather was a patent officer so he has always been obsessed with electronics and HAM and DIY related things. built the TV kits and stuff. I remember when I was younger he was helping me look at an old amplifier and while yes we opened it up and poked around he was very cautious and warned me about discharging caps, about old TV tubes, so on. I think things were at one point much more exposed, but as a result I think people had a different approach or respect for electrical things - knowing something can be dangerous or lethal. I feel a lot of people now assume all electric things are idiot proof and while nonsense scare tactics aren't good, I don't think being too nonchalant is a good approach either. Hell, all it takes is one unmonitored LiPo on a cheap charger with no auto-shutdown to start and electro/chemical fire when you aren't home to set your whole place on fire.

KSS wrote:
This Analog Exerciser sounds and looks familiar. Probably someone like Don Lancaster wrote an article in Popular Electronics.

Don't know whether to feel old or just smile when these older projects appear and the omigod A/C scare reactions show up. Joe's comment about not plugging in an old A/C driven project without first doing some basic investigation is sound and safe advice.

It would be nice if everyone could have experienced the time when Heathkit, EICO, PAIA and so many others offered kits intended for raw beginners with assembly and instructions where A/C was openly possible to be touched during building and testing. People built tube televisions. AC powered oscilloscopes, VTVM,s. I can't remember ever hearing or reading of anyone being electrocuted by a home made device like this. Shocked? Yes, been there myself. But never seriously hurt through many A/C Mains powered DIY projects in my youth and since.

In all the hundreds of A/C powered PAIA kits with similar construction to this analog exerciser out there, has anyone ever heard of anyone being killed or seriously hurt by one? My goodness, to think I walked alone or with friends and sometimes rode a bike to school until college. The horor.

Reasonable caution towards A/C mains is advisable and smart. Fright and scare tactics less so.
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