Sockets + Knobs

Got a parcel from  Tayda and it arrived pretty quickly and the bits are certainly cheap. I now keep thinking of extra things I should have put on the order! Anyway hopefully this will make a few panels to sort of get things rattling along. Tried getting a few knobs and the chicken heads are pretty good -- a little smaller than the ones I have used in the past but quite nice. The Davis 1900 clones I am less enthusiastic about; I cannot get the grub screw to grip on the flat of a shaft OR the normal outside...

921B Mk II

Well having another hack at the Moog 921B. Here we have the Mk I looking on as the MkII gets drilled and it knows that all the expensive parts are about to be removed... The buggered up transistor array layout fix, like a beacon, knows that it's days are numbered... I am planning to make a complete Moog 15 in Euro and this is really the last bit that I need to make sure works properly as a true build before we embark upon that...

Long Time Comming...

On a bit of a whim I built this VCO. I think I have the full house of Thomas Henry VCO's now! This is the last of XR, VCO1, 21C (or LM), X-4046 & the 555. Thomas has always been amazingly adept at getting various VCO devices to perform for a synth environment. This is the 8038 VCO that is from his VCO Cookbook. I bought the chip about 4 years ago but the book has only recently became available again. This is the layout from Fonik's web site but I only built one channel. It roared into life immediately but I think it will need more tweeking as the sinewave is a bit skewed...

Climbing the Ladder

Put togther another variation on the Moog VCF ladder design. I had some spare LM394 matched transistors to use on ALL the pairs for this one... Haven't quite got around to firing this up yet but pretty close...

Entwicklung Bau VCF

Taken a bit of a break from the Bergfotron VCO and whipped up a few boards last week. I know... what about the panels... This is quite an intersting VCF uses a different sort of OTA, the LT1228 from Linear Technology. It was designed by Stephan Winter for (I think) his final year project. The entire synthesizer is written up here. I was only really intersted in the VCF as it is quite different. The layout was quite pleasing as only one link! The tempco design is also quite intersting as it uses a realtively easy to get part and a couple of tricks to get it to 3300ppm/C. I don't usually bother with temperature compensating VCF's but I may try in this case just to so how well it works. The LT1228 seems to have really quite good specifications -- I did a bit of a comparison with the LM13700 today and I notice that quite a few parameters are missing from the LM13700 datasheet compared with the LT1228 which suggests that they probably aren't to special... The LT1228 is fairly expensive though... but not as much as a CA3280!

So where are all the panels?

Was going through the two large boxes that constitute the rather large number of boards that have been etched, stuffed and variously debugged and qualified to some extent then abandoned... This is YuSynth's ARP VCF that actually works really well! I plan to put in an order for more of the polycarbonate panels and the Cliff sockets and the chicken head knobs and make them a bit more useable rather than twisting the odd wire together... When I look at the gloat thread of muffs and the 2013 build pix on e-m i am amazed at the finished panel quality -- particularly the very black one that someone did recently -- so it really is time to get it looking good!

According to Jung

Typical! After berating AbeBooks on a public forum it turned up... whoops... So that Karma is dished out the damn book doesn't have a description of the circuit that I bought it for!! It must be in one of his other books and since this book ended up costing me about $100 when you include the money shelled out for the first one that failed to show last year I don't really feel that inclined to go after the other ones. Having said that this book does have quite a lot of interesting articles -- particularly a section about Norton Amplifiers. Kind of wish that they would just put them on Lulu for $15-$20 bucks. I am now thinking that I might ask Bernie Hitchens as he mentions that they did an investigation into the Jung trick with modulating the power lines of the CA3080 in Electronotes En#63 -- had a bit of a look inside a LM13700 and seems like it should also work for that, but obviously effect both OTA's at the same time (which for Ian Fritz's Wood Wind waveshaper would be fine!)