A few days back, I binge watched all of the YouTube interviews with Erica Synth founder Ģirts Ozoliņš. In one video, he complains that most DIY kits no longer include schematics, so it is tough to learn anything. I think he would be happy to hear that you are learning how to debug circuits with one of his modules.
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One very nice thing about mistakes, though it only happens very very occasionally, is they can lead to real innovation.
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I find that a very helpful thing to do. If I’m frustrated with something I’m working on (or stuck, or just can’t stand looking at it anymore) I’ll just knock out some easy project that’s on my list and then get back to the main project. Kind of like hitting my reset button.
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I’m going through the test point schematic that is provided in the github zip file, and i’m realizing that I can’t measure frequencies. If i test the voltage and its less than 10v ptp, could i use my speakers to monitor the frequency of parts of the circuit by running it through my eurorack?
or do i need an oscilloscope?
How good are your ears ?
Obviously a scope does stuff your ears can’t.
Scopes show positive or negative voltage levels at peak -OR- DC. It will measure very low voltages, and much higher ones too.
Scopes show frequencies outside your hearing.
Scopes allow you to observe very tight timing events. ( Like measuring the speed of a bullet ! )
Multitrace scopes can show the relationships between two or more signals.
Scopes can be made to trigger on signal events.
Scopes can show glitching sorts of noise, or higher frequency noise.
Scopes can do some low level examination of digital data.
Scopes let you look at signal edges, and measure pulse widths, and that sort of thing.
Scopes are much less likely to be destroyed by things that might damage a regular audio circuit.
Scopes can do a lot more too, depending on the scope.
Features built into some modern oscilloscopes
- Multiple Inputs
- Complex Triggering
- Storage
- Frequency Counters
- Signal Generators
- Spectrum Analyzers
- Mixed Signal Scopes
- Digital Signal Decoding
- Simple Protocol Analyzers like for I2C or SPI
- Ability to connect to a computer or the internet.
If all you need is to gauge a pitch, and tell if a signal is approximately a sine wave, or approximately a square wave, or approximately something else, your well trained ear can get you that far.
ADDED : Oh yeah, if your scope has an XY mode. you can draw fun Lissajous figures.
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Thanks for the reading!
Okay I’ll see about getting a scope
They’re nice but not essential for debugging and calibrating kits.
Where stuff like that becomes more valuable is in circuit design & development.
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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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