The most complicated effect I've built so far so I have to say I was actually a little surprised when it worked as I fired it up for the first time! Just wanted your thoughts on one aspect though. This is the first time that something i've built started to act up later than on the building phase. I'll try another chip and we'll see how it goes. Does that space-sitar description sound like that locking issue the earlier revisions had? I'm pretty sure there is just something fairly simple i've missed. I'll get some sleep, go to work and figure this out after that tomorrow. My best guess is that whatever burnt the regulator might have done some damage to the PT2399 as well. Suddenly it started to sound really crazy. But that's like using bigger fuses to prevent them from tripping.Īre there any simple solutions to protect regulators? I could swap the regulator for 7805, which is rated 1A. I guess it seems like i have some ground leak in there somewhere. But i don't thing that in normal circumstances PT2399 could ever draw more than that 100mA. Best not use that adapter with these regulators i guess. Swapped it for a fresh one again and it worked. Everything worked like a charm again.Ĭouldn't believe that the adapter had burnt the regulator, so i tried with the wall adapter again - it burned the regulator right away. Swapped it for a new one and switched that wall wart for a battery. Which shouldn't be enough to burn the regulator. Measured the wall wart, and it says 9,3V. Checked basic stuff out, and noticed that the regulator gave out only 1,2V. Plus the vibe/chorus switch was mute on the other position. I sticked my cheapo wall wart to it, and it sounded strange. Started to play with mine today just for fun. It would be easy enough to change it back if necessary, or even add an additional gain stage and maybe an overall volume control, but that would mean a bigger layout or a small addon daughterboard of some description. These haven't been tested and I don't know how they might affect the output volume but they're definitely worth a try. Or if you wanted the dry signal always present (the Chorus/Vibe switch will still be able to remove it completely if you want) then you could go this way instead:īlend 2 would go to the output, Blend 1 to ground. So the pot will blend between the modulated PT2399 output and the dry signal coming from the NE5532. With an additional cut between the new cap's leads. +12 V connects to pin 8 and -12 V connects to pin 4.To add a mix/blend pot, you'd need to remove the 100n cap at the output (the smaller one below the 10u cap) and add another below the other 100n output cap underneath IC2. Or you can just use a TL072 in which case there are only 8 pins and 1, 2, 3, 5, 6, and 7 are connected the same as with the TL074. You should connect pin 8 to pin 9, connect pin 13 to pin 14, and connect pins 7 and 12 to ground. If you use a TL074 you should not leave pins 8, 9, 10, 12, 13, and 14 dangling. They’re drawn in different parts of the schematic (or not drawn at all) but all are part of one IC. (pins 5, 6, 7) there are two more not shown, pins 8, 9, 10 and pins 12, 13, 14, which are the two unused op amps, and finally there is this piece: There are five pieces to this one IC, here is one: And in fact a TL072 is shown on the stripboard instead of a TL074. It’s kind of silly to use a TL074 here unless something else is being added to the circuit that uses more op amps. A TL072 contains two, a TL074 contains four. OK… I said TL072 because only two op amps are used. These are bypass capacitors and while the circuit will probably work okay without them, it’s best to add them. Ideally they should be located right next to those pins. Two 10 ♟ electrolytics, one from +12 V to ground and one from -12 V to ground, both located close to the power header, and three 100 nF ceramics, from +5 V to ground near pin 1 on the PT2399 and from +12 V and -12 V to ground near pins 4 and 11 on the TL072. I think that’s it for the power distribution.Įxcept that there really should be some capacitors added to this circuit. You see +5 V (from the L7805) is to connect to pin 1 on the PT2399. Tells you +12 V should be connected to pin 4 of the TL074, and -12 V to pin 11. (Not all modulars use ☑2 V, ☑5 V is rather common, but Eurorack and Kosmo use ☑2 V the Eurorack specification actually calls for +5 V to be supplied too, but usually Eurorack systems just distribute ☑2 V and if +5 V is needed it’s done in the module with a regulator, like this.) It’s providing power to a 5 volt voltage regulator (L7805), which is where the +5 V comes from. This is a Eurorack style 10 pin power header:Ĭonnects wherever you see +12V marked, for instance here:
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