Awesome illustrated guide!
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Yeah, I agree that it’s a silly name, but it’s the name we used in those days. You might catch me referring to Veroboard, too. My brain usually operates on a germanium substrate, which should explain everything.
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Still no luck for me on this one.
I’ve tried a few different 2N3904s and a couple S9018s with 18v from two 9Vs in series.
Including some pics in case you guys can see if I’m messing up the circuit somehow.
Also using a 10uF cap as it’s all I have… maybe it oscillates beyond the visible scope?
I may be missing it, but I don’t see any power going to the breadboard?
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10 uF is 100× smaller than 1000 uF so if it oscillates it’ll oscillate 100× faster, which is definitely too fast for you to see individual pulses. Did the earlier steps work as expected, up until you added the transistor? Including the LED lighting up briefly when you did the switching yourself?
What supply and LED voltages did you measure?
(You can get a rough idea of the expected speed simply by multiplying the resistor value with the capacitor value; that’ll give you at least the right order of magnitude for the cycle length, in seconds. In your case 1000 ohm × 10 uF = 1000×10×10^-6 = 0.01 seconds, i.e. 100 Hz. To calculate it more exactly, you need to know when it turns on and off.)
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Any of this transistors - including old can-types - will be better than S9018 for 12v? I will try to debug my setup with S9018, because I still had no luck after adding CV input (vactrol).
List - https://docs.google.com/spreadsheets/d/1Uc5IQkfyYyc6F4a9HeAyHm1NZzXp7JpVXM0wtl_J_ik/edit?usp=sharing
is it work without CV ?
Worked if I connected AUDIO OUT to positive LED leg, not to the positive capacitor leg. If I connected vactro same way, pot stopped working until I connected both LDR vactro legs.
already try without Vactrol, maybe take the tutorial from the beginning
I build the oscillator and the LED blinks and I connected the speaker.
Variant A
Speaker to Ground and to the 100k Resistor: Speaker makes no sound
Variant B
Speaker to Ground and to the positive leg of the LED: Speaker works! (Basically the LED and the Speaker are now parallel in the circuit)
My conclusion: The 100k Resistor is to much for a normal speaker and I need an Amp in between them?
Quoting myself from a Patreon post, where someone was experimenting with a 8 ohm, 0.2 watt speaker:
The 100k assumes that you’re feeding the signal into an amplifier or powered speaker, not directly into a speaker element. The very low impedance may affect the oscillator operation a bit, and you may want to experiment with at least some resistance to limit the current and maybe a capacitor on the way out to filter out the DC component, to reduce the risk of damaging the speaker (note that applying the full supply voltage over an 8 ohm impedance will damage the speaker, e.g. 12 V over 8 ohms is almost 20 watts, but hopefully the 1k resistor in series will deal with that). Or you can just add the 100k again and plug it into some cheap computer speakers instead, and let those deal with things.
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Thank you! That was the thing I assumed yesterday, but I was to tired to make sure, that I was right!
I guess I’ll try out variations of Resistors + Potentiometers for Volume control.
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It works (ok, 4 out of 5 oscialltors) - I learned a lot in the last two days and made all the things wrong I can think of, including breaking the lid, but now I’m quite happy for now.
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I try to learn electronic through this project therefore I have drawn this simple oscillator schematic, it includes tone filter and VC control. Project is little easier to understand this way !
Do you see any mistake ? Does C2 on tone filter and vactrol are in the right direction ?
I am stile waiting for material to arrive so I cannot test this schematic yet.
My final goal is to use a CNC machine to make a custom circuit board with those oscillators, simple LFO and simple envelop filter. So I will keep extending this schematic.
I will keep sharing it! hoping it will help other people to get it right !
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How did you mix the 5 oscillators together? Did you just connect the outputs together or did you use a mixer circuit?
My oscillators work seperately. But when I connect the outputs together the output gets verry low.
While looking for simple flashing LED circuits to practice on, I was sure there was a simpler one than those astable multivibrator thingies. Then I saw one using the reverse avalanche breakdown and the penny dropped that that’s essentially the super simple oscillator. After reading some of the threads and watching all the YouTube videos, I think a few of these to go alongside my MFOS WSG would be cool. However, I’ll be running 9v, so the only transistor that’s suitable is the SS9018, which I can get off eBay.
I’ve only got 1µF and 220µF electrolytic capacitors though, so I need to get some that are more appropriate. Before I buy some similar to the ones listed under the triple skull drone, further down the super simple oscillator page. Do the values of the capacitors depend on the input voltage…? So if you’re running 12v - 18v, then 100µF, 33µF and 10µF are fine, but if you’re running 9v you might want slightly different ones…?
Yes – the capacitor charge time is proportional to R×C (yes, resistance times capacitance is time), and a capacitor that’s charged through a resistor will have reached >99% of the voltage across that circuit after 5×R×C seconds.
However, here the transistor will open before it reaches that point, so the exact frequency depends on both the supply voltage (that charges the capacitor) and the transistor (that discharges it, at some point).
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And note the triple skull used a different transistor, 2N2222, so that’ll change the frequency too.
My guess is neither the different supply voltage nor the different transistor will affect the frequency by much more than a factor of 2 or so, though. And if there’s a pot on the input voltage, you’ll be able to adjust the frequency over a decent range.
Bottom line: Just get yourself 5 each of about 5 capacitor values from about 1 µF to 100 µF and play around with them on a breadboard, or build the oscillator with a pin socket so you can plug in different capacitors, to see what you like best.
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PS. In case anyone wonders about that bit, Wikipedia provides these expansions:
and if you multiply e.g. V/A with A·s/V the A and V cancels out and the only thing left is the seconds.
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Need to get that on a t shirt.
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