dumb question - with an esd wrist strap for static when working on a pcb build, where do i attach the clip? im working on a wood table with metal legs on a wood floor.
I built lots of Befaco kits, the Mixer and the Output are easy enough to start with but I would recommend -as others stated before- to solder some entry level educational kit or cheap pedal circuit. Befaco kits come with pre-soldered SMD components so it is definetely the next level after soldering some pedal circuit. Check also this channel for completely DIY modules from scratch:
Last but not least, you should start with full DIY kits at least in the beginning because finding the exact components listed in a Bill of Material (BOM) ain’t so easy expecially in pandemic times…
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New Erica synths DIY kit just came up!
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Cool, Will check It out
You’d attach to a good, known earth THROUGH A 1MEGOHM RESISTOR.
Sorry for the shouty caps but it’s essential you don’t connect yourself directly to earth if there’s any possibility of coming into contact with mains power. The idea of the strap is that you don’t build up a static charge which can then fry sensitive components. The resistor will still keep you at ground potential.
As an aside I’ve never managed to kill any chip with a static discharge in donkeys years of tinkering. Modern IC’s have good ESD protection built in. I’m not saying you can’t kill one but I’ve not used an earth strap in years and my wooden topped workbench is on cheap carpet. Maybe I’m just lucky…
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I appreciate the shoutyness and response but i dont have a 1 megohm resistor. Took physics at university over 12 years ago so a little rusty on this. If you can dumb it down for me can I just attach it to something metal? Just playing it cautious bc this codec chip took a while to get from HK and it’s pretty rare if i do fry it. thx!
also, do i need flux? was planning on not using it first round… i have solder with built in resin or flux, not really sure, haha.
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Music Thing Modular do some great kits. Pretty easy to put together, I’ve made the spring reverb and Turing Machine. As well as some useful attenuators and mults, they can br pretty simple and rewarding to put together. I’ve had a couple of disasters, but not wasted too much money, however it put me off making the RE-303 or RE-909!
Good luck, I really enjoy making the small bits!
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Are you in the uk? The reason I ask is that in the uk you can get a 3 pin plug top that you attach the strap to that has an integral 1M resistor. I’m not sure if there’s an equivalent for other socket outlets in other countries.
Re flux. I’ve used flux paste in the past but I just use flux cored solder these days. I’ll caveat that by saying I pretty much only do through hole work and I’ve very little experience in surface mount soldering. Works fine for me.
Edit. The shoutyness was just with safety in mind. If you’ve got a low resistance path to earth (strap on your wrist connected directly to a low impedance earth point) and you’re unlucky enough to touch mains voltage then a large current will flow through you! Not good! By introducing the resistor in series between you and the earth point then you limit the maximum current that can flow. Ohms law says that with an assumed supply potential of 240v and a series resistor of 1M the maximum current that can flow is 240/1,000,000 = 0.00024A or 0.2mA.
From a purely ESD point of view the resistor slows down the discharge to earth in the event that you do build up a charge. With a low resistance the charge will flow to earth quickly and that ‘spike’ (when the static charge flows to earth almost instantly) could be enough to damage your device. By slowing down the discharge you flatten that spike. It’s a simplistic description but I’m sure you know what I mean.
On safety – best to stay completely away from anything with that sort of power. Meaning all circumstances. ( That’s part of the reason i earler suggested small batteries to test circuits, rather any higher current power supplies, or at least have the current turned way down with them. )
Also note that ( at least in the US ) a lot of older homes, have three wire outlets that are improperly not connected to ground with the third connector, as well as the outlet electrical box. Make no assumption on those outlets being grounded without testing – there are cheap plug thingies with LEDs that are useful for that.
Also note that while an electrical component may be exposed to ESD and continue to work, ESD can weaken a component so as to decrease its life, and create latent problems. Protection is still important !
Here’s a good document on ESD protection :
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might be of interest:
Moritz Klein has a new set of modules with Erika Synths:
do check out the manuals
LOTS of good info for those just starting out
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All very good points @Jukka. Here in the UK the plug with the LED’s was known in the trade as a ‘Martindale’ as that was the brand name. Maybe I should have explained a bit better than I did. That’s what I meant by a good, known earth/ground. You’re spot on about keeping away from high voltage/current sources though.
I got a good shock from installing an “old fashioned” POTS telephone line. You don’t think of a telephone as dangerous but people used to die from electrocution from the telephone. Telephone in the bath tub – zap.
Also appliances, particularly older ones that are improperly grounded can be hot, though again you might not feel it until you touch that appliance and an earth ground at the same time. Refrigerator to kitchen tap – zap. Been there, done that.
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On the second day of my apprenticeship I managed to ‘gently stroke’ my finger across two phases whilst pulling cables into a distribution board. Thankfully the fall from the step ladder wasn’t too bad! It was an occupational hazard as an Industrial Electrician back then when you were expected to work inside live boards, drilling holes and pulling in cables etc. My gaffer dropped a spanner inside a live bus bar chamber which unsurprisingly vaporised. He was lucky to keep his sight. The boss’s son wasn’t so lucky and was killed at work in a separate incident. And people decry the health and safety culture…
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I would advise extending that same caution to newer houses as well. As someone in the building trades I see absolutely terrifying electrical work more commonly than you might think. In many areas (where I live, for example) any homeowner can do their own wiring and inspectors aren’t as thorough as they ought to be in that scenario.
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So what’s the outcome?
Were you able to swap the pots around and get everything working?
My fume vacuum arrived so I’ve been practicing soldering through hole joints. But the things are so tiny I’ve had to order a desktop magnifying setup cause I must be blind.
I ordered some MIDI breakouts for Teensy from a guy selling them off Tindie and they arrived. I don’t think I’ll attempt to put them together until my magnifier arrives and I do more soldering practice.
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I switched the pots around, but it was messy. I am pretty sure I’ll need to make a few flying traces.
I won’t solder the extra structural terminals of potentiometers until after testing in the future.
I leaned that it’s easier to heat the solder and inch a component out of its socket than attempt to remove all of the solder.
I found another mistake. I switched a diode on the control board. The diode wasn’t damaged but I had an extra and replaced it in the correct orientation.
The lfo and input gain are functioning, the led diodes in the overdrive circuit now show activity. There is a light that “bounces” between the two. However I am still not getting the delay output. I receive audio from the wet output and the main out.
I’ve started to go through the schematic and test the few test point values scrawled on the pdf. But I only have a multimeter so I can’t test some of them.
I’ve reflowed and cleaned a lot of the board and double checked ICs. I’ve checked for heat, which thankfully hasn’t been an issue.
I’m going to walk to the library tomorrow to print out the schematic and attempt to highlight the audio signal path.
It took me some rooting around to find the correct resistor values for a few parts around the overdrive circuit.
I feel closer, and I’m open to direct advice about wether or not to purchase an oscilloscope.
Also, thank you for asking!
I’d recommend getting some desoldering braid. That way you can wick the solder away when desoldering. Then you can use it to clean up the pads on the board.
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Don’t live in the UK and I think my house was built in 1930s so might be risky, thanks for the explanation. Ended up just skipping the static wristband.
I did manage to do a shite job on my first go round. I get the hang of soldering but a combo of super tiny components, poor lighting, no magnifying glass, and trying to get the right temp on the iron was a challenge.
Anyone suggest how to move forward on this build? How good does a joint need to be for it to function well?
can add more pics if it’d help, thanks!
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So did you solder those SMC’s without flux? If so, that’s pretty decent. But re your question above about flux, it can make small things like that much neater, but sometimes the component might float off if you blob on too much. Best hold the component down with a tweezer. FWIW, I usually don’t bother with flux on most thru hole work.
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