I've now got a couple of Holtek HT8950 chips which I'll try out one of these days. That was my only foray into the world of SMDs (quite a few years back) and I managed to fry it! It's a shame, because I wanted to try some pitch shifting at the time, but I didn't fancy spending about 8 or 9 pounds for a replacement. I assume that's the same as the MSM6322 chip. SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube I have a recording of it somewhere so I'll look it up and post a section. The output back to the input! especially with random control of the binary input lines. great fun, but even more fun when you add I did some tests using my modular lunetta to control it with a CD4050 as a level shifter to protect the chip.
trying to lift the pin of the PCB without breaking it and then soldering a wire to itīut I got that done aswell and after this fix it worked as it should And also by cutting the other side of the trace What I hadn't realized was that the trace was going underneath starting from under the chip. Pitch but not binary, it still did the up down thing.Īfter taking another look at the PCB and doing some more measurements I discovered that the mode pin was actually still grounded eventhough I'd cut the So I stuck it in a breadboard wired it up, crossed my fingers and powered it up. Next came the fun part soldering wires to the chip and cutting some very small traces. I put the connector in from the top and added some perf on the bottom to
Of perfboard as a template to drill a row of 10 evenly spaced (0.1") holes. I first scraped of some unused traces to prevent any shorts, and then used a piece To make it easier to test the chip I mounted a connector to the PCB. However I don't want to fry the chip so I have to I could make everything I add runĪt 5V but that doesn't leave much headroom for the audio and I will probably use a 12V supply anyway. The voltage regulator is an 78L05 because the chip runs on 5V. it has a build in ADC,ĭAC, low pass filters and some opamps, even a spare one to make a microphone preamp (wasn't used in this mixer). The chip itself is quite easy to use without a lot of external components. Possible to add the 17th step with some extra logic). Using the binary inputs lines will give you one less pitch option, one octave higher, but you get a lot more fun in return. that will make it a lot more fun to play with One is to change the pitch in 17 steps by two switch inputs, and the other is select one of 16 steps by four binary input lines Two pitch control methods can be selected. But then I read the datasheet and found out that
The voice changer on the mixer was controlled by three buttons pitch up, pitch down and a 'reset' button. And the best thing is there is a datasheet posted for the OKI chip! My search led me back to, this thread to be precise. Which leaves cutting a part of the PCB.īut before I started doing that I first wanted to know if there was any info on the chip so I could see which components I'd have to leave on and where It's an SMD chip (SOP24) so removing it wasn't really much of an option but I don't need the preamps and those might The voice changer section is made with an OKI M6322 chip and it was mounted on a PCB that also hasĢ microphone preamps. Way I can easily see how those are wired up. All the boards are wired together with connectors and this I started by drawing a schematic of the whole thing, or at least the main mixer section. There's the board with the in/output connectors which has buffers and also the PSU section, the main mixer board, anĮqualizer mounted to a panel with slidepots, a headphone amp, a VU meter and of course the voice changer. A nice thing about how it's build is that it has several PCB's Useless over the years and I don't use it anyway I decided to take the whole thing apart. Years ago I got myself a JBsystems LAM91 DJ mixer, I think it was actually my first mixer allthough I might have build a simple one myself before that.Īnyway it has a build in voice changer which I've always wanted to take out and use as a standalone effect. Subject description: with keyboard control and more goodies Mark the topic unread :: View previous topic :: View next topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus Register Profile Log in to check your private messages Log in Chat Room FAQ Calendar Search Memberlist Usergroups Links
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