Hi all, a while ago I posted about the hooting owl project LMNC covered from the December 1972 issue of Practical Electronics. I want to recreate this in a eurorack format with control over the pitch of all 3 multivibrators along with pitch and trigger inputs, but for now I could do with just getting the original circuit made. I’ll be making it on stripboard, but first I need to figure out how where to put the components (in case you couldn’t tell, I’m still pretty new to electronics).
How would I go about starting with a schematic and ending with a stripboard layout for me to follow? Ideally I want some sort of program to just look at a jpg and magically turn it into a stripboard layout, but I don’t think that exists. Therefore I’m guessing I need to make a layout myself, which I don’t know how to do yet so any advice and software recommendations would be great!
Here’s the original schematic (page 43):
I just tried to remake it closer to the way I want it in EasyEDA, first time using it though so I’ve probably made some mistakes:
Lots of trial and error when I do it. I tried doing the first oscillator, which is what I’d start with if I were doing the whole thing. Usually I’d start with ICs but there are none here, I started with the transistors. At first I put them next to each other horizontally but then realized the full circuit would end up very wide that way so I put one above the other. The strip between will be the ground the emitters connect to, and I put those jumpers in:
Next the components nearest those, C2 and C3. It’s tempting to try to make them (rotationally) symmetric but again you end up making it too wide that way, so one goes above the other:
Then connect each to the opposite transistor’s base. I also put in R2 and R3, which connect to a common strip at the top.
I decided it’d be convenient to have a ground strip at the top too so I put a jumper in for that.
Then I could add C1.
And finally R1 connecting to the upper ground, the common strip with the resistors, and the collector of Q1.
Hopefully no mistakes there! Having done that it might be possible to just replicate that arrangement for the other two oscillators to the right, and then at the far right put in the output stage. Probably I’d make a trace cut on the center ground strip (as well as almost all the other strips of course, except the top ground and the strip below that) and use that same strip for the emitters of the next two transistors, then another strip cut, then connect the next two transistors and R12, R13, C9 to that. Connecting one stage to the next might turn out to have pifalls, I don’t know, but if that works out it’d be nice not to have to re-think the layout of each oscillator.
That’s super useful, thanks! I’ll look into it properly later and let you know how I get on with it. I’ve just installed KiCad as suggested by jaradical so we’ll see if I can make the other two oscillators and output in a stripboard layout. Thank you for the insight into your steps!
By the way there are some very nonstandard capacitor values in there (maybe they were around back then) but there should be no problem with substituting nearby standard values.
Yeah, I ordered a bunch of kits of resistors, caps, diodes etc of common values. I tested one oscillator on a breadboard and it worked well enough, although I think I swapped the 10uF (C8) cap with 22uF or something cause the sound would decay super quickly and then take ages for the circuit to make any sound other than a pop when turned on. I don’t know enough to diagnose why that happened, got around it though!
Since reading an schematic is part of the process I think this question might fit here:
When on a schematic (the 1114 filter to be precise) are several tags with the same name they are ment to be connected right?
I couldn’t find info about the matter
e.g:
Indeed - those are global labels - anywhere you see them are all connected together.
You’ll see similar things for power and ground supplies, but they usually have their own special little symbols like the ones marked GND, -12V etc in the schematic, so all the symbols marked GND are actually connected together and all the -12V points are connected together.
I’ve just finished making a stripboard layout for the original circuit, I’ve attached the un-optimised version. Even optimised for space though it’s 45 columns, which is bigger than the stripboard I’ve got. If you could check this layout is correct to the schematic that’d be great, and if you could help cut the space down that’d be amazing.
I haven’t checked this carefully so there may be errors. In doing this I realized your schematic had the pots wired as attenuators when they should be variable resistors, so I corrected that.
Ah, that probably works better, I’m still new to all this stuff. Here’s another version I made of the original circuit, this time in a way that will fit on the stripboard I have. Ignore the error R9 is showing, it did that on the last layout too even though it’s fine, think it’s something to do with the netlist I made.
It’s very messy but in theory it would work. I need to replace B1 with a 2x5 header to fit in with eurorack, and replace LS1 with a jack socket. Then I’m gonna go through the breadboard and test pots in various places to see what happens, but if I don’t get to a place I like then I’ll look at your layout. Thank you regardless!
Oh also, what software are you using to make them layouts? I’ve been using KiCad for the schematic and netlist, then VeeCad for the stripboard layouts. It’s all rather old software it seems, rather rough around the edges.
