modified bontempi memoplay

Some clips of my circuit bent bontempi memoplay + sequencer + filter + dividers, pll etc.... Had some fun with a bontempi memoplay keyboard and built some extra circuitry to improve it sound capabilities :) It has a 4051 based sequencer, filter, 4520 dividers for sounds, 4046 pll. The circuits are controlled with the sequencer using simple led+ldr.

Category:

Music

Tags:

• koelse
• bontempi
• circuitbent
• circuit
• bending
• experimental
• electronics
• diy
• synth
• sequencer

[farmerglitch]

very impressive - just grabbed one today for a quid here in the UK - would apprciate any board hook-up points you could show - first on my list is a divider I think !!

[hvahanis]

The pitch trimmer can be easily removed and use a bigger value potentiometer instead. You can take the sound output from the base of the amplifier transistor and feed it to a divider (cd4520,cd4040 or other cmos device). Datasheets of the cmos chips basically tell you what to do. Easy rule is to pull down (100k to ground) the cmos inputs then feed them with signals from your bontempi. You can also power the chips from same batteries. Mix the cmos-outputs with resistors or diodes.

[aliencall]

wow! i have find one of these,you have a lot of circut inside true?have a pcb scans or fhoto of your skematic used?

pitch and tempo are trimmed (sot w pot) but i can modify sound whith original pcb?

thanks

[hvahanis]

there is five main functions added: 1. 8-step sequencer wich has a cv channel and a pulse channel: built around cd4051, 2. a filter: same as in MFOS wsg 3. a 4520 giving divided outputs of the sounds (lower octaves) 4. phaselockedloop cd4046 (not working as i imagined but nice anyways) 5. 4011 based modulator. Unfortenately i didnt make any pcb, all was built on veroboard. Schematics from cmos datasheets, web etc. I didnt do much with the original pcb just pitch modification.

[ChrisLody]

Wow, that's impressive stuff! It sounds really amazing, much nicer than totally random bending. So you're using a logic chip based sequencer controlling this keyboard via a vactrol type setup right? So does the ldr of the vactrol replace the timing/tuning resistor or is it sequencing the filter or something? I really like the idea of enhancing old keyboards like this but have yet to try it myself.

[hvahanis]

Thanks. There are 3 ldr+led "channels" one for pitch of the keyboard, one for filters cutoff and one for frequency of the pll. All are controlled with the sequencer either with pulses or with cv. I used transistors for the leds so that the control signnals are fed to base of each transistor.

[Breenophelan]

cool.. skematics



[lavaguechannel]

G R E A T !

[aliencall]

Thanks a lot :) i start my experimentations

[sneakytraxx2010]

top

[1981analog]

Oh my god, this was my first ever keyboard! It was AWFUL!! It didn't even play back in time!

[ChrisLody]

Clever stuff. Its Really turned this keyboard into a tweakers dream. The only thing I don't really understand is the phase locked loop, not really sure what thats all about. Did you have professional training for this or teach yourself? If so can you recommend some good websites? I'm still learning how to abuse logic circuits after recently getting back into electronics. Cheers.