Search found 229 matches

by wahee
Fri Apr 16, 2021 4:03 am
Forum: Music Tech DIY
Topic: RAM bank addressing
Replies: 2
Views: 146

Re: RAM bank addressing

hi thanks for the feedback. The switch is physically close to the RAM IC but will maybe put in the 2 resistors as you suggest
by wahee
Thu Apr 15, 2021 2:40 pm
Forum: Music Tech DIY
Topic: RAM bank addressing
Replies: 2
Views: 146

RAM bank addressing

hi all been making myself up a small RAM cartridge for my JX8P, a M16c copy I think I have the basics ok A0 to A0 etc I started to get greedy and thought about using a larger EPROM and accessing 4 banks So on a 64k IC like the FM16w08 rather than the original to access the higher banks I was reading...
by wahee
Thu Apr 15, 2021 12:18 pm
Forum: Music Tech DIY
Topic: making a ram cartridge..
Replies: 5
Views: 229

Re: making a ram cartridge..

The Ramtron FM1608 looks like it may well be useable
by wahee
Wed Apr 14, 2021 10:08 am
Forum: Music Tech DIY
Topic: making a ram cartridge..
Replies: 5
Views: 229

Re: making a ram cartridge..

yes hopefully. It would be better to get a non CMOS EEPROM ram chip rather than a TC5517 although I have a few of these.
Although I think the timing is more critical for EEPROMS but other than that, I have the cartridge designed thanks
by wahee
Wed Apr 14, 2021 9:31 am
Forum: Music Tech DIY
Topic: making a ram cartridge..
Replies: 5
Views: 229

Re: making a ram cartridge..

thanks very much for this. Yes I was able to find an image of the cartridge and it's as you say. I also looked inside my Casio cartridge and it has pull up resistors also
by wahee
Wed Apr 14, 2021 7:58 am
Forum: Music Tech DIY
Topic: making a ram cartridge..
Replies: 5
Views: 229

making a ram cartridge..

hi all

just wondering if anyone knows what these resistors are from a Roland MC16 cartridge

I think they look like 10k bussed resistor networks, pulling the lines to VDD

Part TNC14A103M

RESISTOR NET.JPG
by wahee
Wed Feb 03, 2021 1:06 pm
Forum: Music Tech DIY
Topic: synth inverted gate pulse?
Replies: 18
Views: 243

Re: synth inverted gate pulse?

hi basically yes, I will add a current limiting resistor as you suggest
by wahee
Wed Feb 03, 2021 11:41 am
Forum: Music Tech DIY
Topic: synth inverted gate pulse?
Replies: 18
Views: 243

Re: synth inverted gate pulse?

so I think I have finally solved it. when any gate signal was inserted into the EXT GATE at the back of the synth, the pitch gradually rises. Not sure if there's a fault in this synth of ig it's just weird I noticed that if I short the +12 to -12 on the keyboard connector, I get gate. So I needed a ...
by wahee
Wed Feb 03, 2021 4:33 am
Forum: Music Tech DIY
Topic: synth inverted gate pulse?
Replies: 18
Views: 243

Re: synth inverted gate pulse?

I have managed to get the pitch CV pretty good by manually tuning each note. Although rather laborious it worked quite well. Overall the MIDI to CV has turned out to be useable if a little quirky. or at least I though I had tried this morning and the external gate won't trigger the synth unless T200...
by wahee
Wed Feb 03, 2021 4:31 am
Forum: Music Tech DIY
Topic: synth inverted gate pulse?
Replies: 18
Views: 243

Re: synth inverted gate pulse?

i think it might be noise on the keybed CV S/H input. with no keys depressed, that input is floating, and each new gate samples this floating voltage. capacitive coupling and mains hum can easily effect that node, since its such high impedance. it would be nice if it was normaled to the external CV...
by wahee
Tue Feb 02, 2021 7:01 pm
Forum: Music Tech DIY
Topic: synth inverted gate pulse?
Replies: 18
Views: 243

Re: synth inverted gate pulse?

hi it doesn't happen with the keyboard when the CONTROL is set to KBD. I actually found the MIDI is ok and the problem stops when CONTROL is set to OSC, although the drift is actually the LFO it seems ,even though it's off If I have a little LFO on the sound, the issue is gone and the MIDI to CV wor...
by wahee
Tue Feb 02, 2021 6:46 pm
Forum: Music Tech DIY
Topic: synth inverted gate pulse?
Replies: 18
Views: 243

Re: synth inverted gate pulse?

i'm actually starting to think that the synth is modulating ever so slowly even with the knobs at 0
experimenting more...
by wahee
Tue Feb 02, 2021 6:06 pm
Forum: Music Tech DIY
Topic: synth inverted gate pulse?
Replies: 18
Views: 243

Re: synth inverted gate pulse?

hi yes the gate goes in to the back socket and so does the CV. The pitch rises when a note is player and the note value is held so every keypress raises the pitch slightly higher. It takes about 50 key presses to get to the next semitone. Holding a key makes no difference as the not is stable, it;s ...
by wahee
Mon Feb 01, 2021 6:12 am
Forum: Music Tech DIY
Topic: synth inverted gate pulse?
Replies: 18
Views: 243

Re: synth inverted gate pulse?

yes it's MIDI to CV - gate to the T2000 5v works or as a trigger and the circuit will work ok to operate the T2000 gate it just seems to add a small amount of cumulative pitch drift each time the gate is operated. This seems independent of the pitch CV. To be honest the T2000 is so odd that's it's a...
by wahee
Sun Jan 31, 2021 6:47 am
Forum: Music Tech DIY
Topic: synth inverted gate pulse?
Replies: 18
Views: 243

synth inverted gate pulse?

hi all I am making a MIDI kit for my Transcendent 2000 mono synth it has rather odd CV and GATE arrangement. The CV is not 1v per octave, but i'm working to sort that out with some Arduino code/tuning. The GATE signal requires an inverted signal. I copied this circuit. From here http://www.doepfer.d...
by wahee
Wed Jan 13, 2021 7:17 am
Forum: Music Tech DIY
Topic: Adding a sub oscillator to the Teisco 60F
Replies: 4
Views: 161

Re: Adding a sub oscillator to the Teisco 60F

guest wrote:
Mon Jan 11, 2021 4:53 pm
sounds great!
cheers, it's actually a decent mod to do
by wahee
Mon Jan 11, 2021 2:30 pm
Forum: Music Tech DIY
Topic: Adding a sub oscillator to the Teisco 60F
Replies: 4
Views: 161

Re: Adding a sub oscillator to the Teisco 60F

replicate the circuits in the mixer section. add a resistor from the 4024 output to the top of a 50k or 10k pot, and then take a 100k from the wiper of that put into the mixer. hi managed to get it sorted. Did as you said. I had to use quite a high value pot 500k. Then a 100k in and 47k out. Gave s...
by wahee
Sun Jan 10, 2021 2:52 pm
Forum: General Gear
Topic: VINTAGE sTIX st-305 DRUM MACHINE ISSUE
Replies: 6
Views: 667

Re: VINTAGE sTIX st-305 DRUM MACHINE ISSUE

that's me, yes got quite far with it, although not completely sorted.
by wahee
Sun Jan 10, 2021 2:13 pm
Forum: Music Tech DIY
Topic: Adding a sub oscillator to the Teisco 60F
Replies: 4
Views: 161

Adding a sub oscillator to the Teisco 60F

hi I have successfully made a very simple 4024 based sub oscillator and have tested it on a scope and it does indeed put out division of the inputted square wave. I wanted to add this to my 60f. I have successfully located the square wave output and the 4024 outputs a divided signal. I have been hav...
by wahee
Fri Sep 11, 2020 6:59 pm
Forum: Music Tech DIY
Topic: Highly Liquid Projects
Replies: 79
Views: 9654

Re: Highly Liquid Projects

excellent post, I have just ordered a CS-01 and a URM2 so will be attempting this. Thanks for the link to the old forum posts. I'll trey and document the install
by wahee
Tue Sep 08, 2020 6:23 am
Forum: Music Tech DIY
Topic: Calling Power supply gurus
Replies: 26
Views: 1087

Re: Calling Power supply gurus

FYI the wallwart is a transformer. there is no way around it. switch mode supplies have transformers. there are designs that do not have transformers. a buck converter for example. I would not show you how to do it because those systems can be deadly if they are not used properly. something you wil...
by wahee
Mon Sep 07, 2020 6:58 am
Forum: Music Tech DIY
Topic: Calling Power supply gurus
Replies: 26
Views: 1087

Re: Calling Power supply gurus

That's great I'll have a look at those devices. I think they are fixed output also.
The circuit is basic synth so nothing major in the capacitor department, just a few 220uf 16v
Thanks for your help with this.
by wahee
Sun Sep 06, 2020 8:19 am
Forum: Music Tech DIY
Topic: Calling Power supply gurus
Replies: 26
Views: 1087

Re: Calling Power supply gurus

CR4 and 6 are not there for the same reason as CR 3 and 5. You can read about them in TI's Linear Circuits Databook, Vol.3. Pg2-436 4 and 6 are for output polarity reversal and 3 and 5 are for reverse bias protection. We do tend to see 3 and 5 more often in DIY published circuits. But 4 and 6 are n...
by wahee
Sat Sep 05, 2020 7:23 pm
Forum: Music Tech DIY
Topic: Calling Power supply gurus
Replies: 26
Views: 1087

Re: Calling Power supply gurus

Very interesting, I always thought I needed a 3 tap transformer to easily get negative voltages, so this was a good if not perfect alternative No need. See this example. Not sure it needs quite so much smoothing capacitance and it only really needs CR3 and CR5 or CR4 and CR6. http://musicfromouters...

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