Hey guys, hope that u’ re doing good!
Here I go again with the super simple VCO, but this time I built the circuit on a stripboard, in case my breadboard is damaged as some of u suggested.
As last time, the circuit isn’t working, and the LED doesn’t even light up, even though the circuit looks exactly like the one in the original stripboard layout. At the beginning I was using regular solder wire for the small connection between the two legs of the pot and for +V and GND, the I tried with jumper wires, but still nothing (red wire = +V, yellow = GND).
Now, my two questions:
Should I buy some proper wire or any kind of conductiove material should do the job?
How should the back of the stripboard look like? Do I have to make connections between the various components on the back or does the stripboard work like a breadboard (I’m using a single sided stripboard)?
Sorry for the stupid questions, hope that you can help me to find a solution!
@Dud is right. You need to put the components on the plain side and solder the ends to the copper strip where the component leg emerges through the hole. Also make sure you clip the component legs off after assembling the circuit (it’s okay to test briefly first as long as you make sure none of the long legs are touching.)
Oh thanks guys ! I put the components on the other side and none of the legs are touching but it still doesn’t work, the LED doesn’t light up. Should I try to solder?
Also, can I use solder wire for the connections or jumper wires are better?
The solder is necessary to produce an electrical connection. It cannot be used as if it’s a breadboard because, without solder, there is nothing to ensure the metal parts are electrically connected as required.
I just tried LMNC’s schematics with the first three transistor types I had within reach, and a variety of capacitors, and they all worked just fine (2N3904 and BC547 BC548 oscillated at 14 V, BC337 at 11 V).
It may help to test the circuit with a larger capacitor (e.g. 470 or 1000 uF) since that lets you see if it’s oscillating – the LED will blink or at least pulse. If you go directly to audio, the circuit may simply oscillate outside the (rather limited) range your gear and ears can handle. If you’re outside the audible range, you cannot really tell what it’s doing unless you look at the circuit through an oscilloscope.
Also make sure that you turn the transistor the right way; the voltages above are with the emitter towards plus (note that for the ones I mentioned, 2N3904 has a different pinout than the others), and with the base pin cut off. It may work otherwise, but possibly at other (higher) voltages. EDIT: Tested all three with the emitter towards ground, up to 30 V, and none of them oscillated (not that surprising). They all still worked the other way around after that adventure, though.
Finally, if you switch capacitors, make sure you discharge them before putting them back in, by shorting the pins (*). While they’re not dangerous to you, the components in the circuit may not like having the contents of a fully charged 1000 uF capacitor dumped through them. This also applies if you make other changes, e.g. changing transistors.
*) ideally, you should discharge capacitors through a resistor to minimize the risk that you’ll damage them, but I don’t think it matters much at the levels we’re talking about here.
has the transistor either the wrong way, or shown from underneath, or mislabeled. If you look at a 2N3904 with the flat face toward you and the legs downward, the left leg is the emitter and that should connect to the pot. The right leg is the collector and that should connect to the LED. (Which is backwards from the way transistors usually are connected. It’s a weird circuit.)
You arnt the only one to make that mistake. We’ve seen that before! Once you get your head around it, you’ll find that Vero/strip board is great! Also I’ve been there with crap breadboard. I troubleshot a circuit for a week before trying a different bread board. I used an old reliable good quality one from the bow defunct radio shack. Worked the first fucking time. Lesson learned, test the breadboard, don’t trust cheapo ones if you buy them. Right now, I have like 5 cheap ones, but I have 1 that I refuse to use.
You need to make sure that the connections between the components correspond to the electric circuit diagram. It is not enough to just solder them to the copper lanes on the strip board. Only when all the interconnections are made then it will work (assuming the diagram, and your soldering is correct).
Doesn’t matter that much, but solid wire (aka solid core, single-strand, Draht in German) is usually easier to work with on a breadboard/PCB, while the more flexible stranded wire (Litze in German) is better for connections between boards, or from boards to front panels, etc.
How do you know the circuit was working if you didn’t see (or hear) it oscillate? Before you start buying stuff, I think you should go back to the breadboard and build up the circuit step by step, verifying each step before moving on to the next one. See here.
! I put the components on the other side and none of the legs are touching but it still doesn’t work, the LED doesn’t light up. Should I try to solder?
