get ready for impact…
as with the previous versions, i’ll update the gerbers and documentation when i’ve tested it…
I think after i’m done with this one i’ll take a break from game boys
as with the previous versions, i’ll update the gerbers and documentation when i’ve tested it…
I think after i’m done with this one i’ll take a break from game boys
11 Likes
Another new module, this time a copy of the famous Polivoks filter -
The core of the circuit is taken directly from the Polivoks schematic but using MC1776 programmable op-amps in place of the original К140УД12 chips, a TL072 in place of the КР140УД8Б and a 2N3904 in place of the КТ315Г transistor. The inputs and outputs are modified for use in a modular synth with two CV inputs (one having an attenuverter inspired by Marc Bareille’s version, but with a very different implementation), and three outputs - lowpass & bandpass (these are switch selectable on the original Polivoks) plus an (approximately) equal-power mix of the two giving an additional output continuously variable between LP and BP.
I wanted to give this a real Polivoks feel, so went for white legends on a black background with graphics inspired by the original Polivoks filter, and also 3D printed some Polivoks-style knobs in a Eurorack-friendly size. I’m really pleased with the way this came out. Also, a quick shout out to Phoxy Design for the really high quality white on clear waterslide transfers they printed for me - very fast turnaround and a very reasonable price.
The filter sounds pretty much like the real thing too. Here’s a quick sample - sawtooth waves (sequenced by a Turing Machine / Volts) into the Polivoks filter, with a fairly high resonance setting and cutoff modulated by a chaotic LFO running a simulation of the Lorenz Attractor. The synth output has some reverb added by an FX2000. The first 20 seconds are pure LP, second 20 pure BP and the final 20 a 50:50 mix.
As usual full details of the circuit etc. are in my Github repositories for anyone who’s interested.
10 Likes
I finally pulled everything out of my cabinet and put together a first pass on a layout entirely focused on two voices, got my newly finished Hero/Sidekicks calibrated, and plugged it in for the first time last night. I couldn’t be happier and I know I’m just getting started. Spent a lot of time focused on the Analog Output wave displacer for moving harmonics, used the dual rectifier to have a plucky octave drop on the front end of the gate, and just got lost in the process I didn’t even start on the second voice.
I absolutely love this thing, am stunned at its quality of tone while maintaining flexibility, and that there’s infinite possibilities to follow.
8 Likes
Hi, I am a little interested in building this filter for myself and I was wondering where you source your MC1776 chips from. Thanks!
My MC1776s came from a seller on Ebay UK in a pack of 5 at a very reasonable price. As of today (28/10/25) they are still available.
Here’s my long weekend progress on my 32 step sequencer build from an old rack mount Sony MkS-8080 Aux bus remote panel.
I’m using a Raspberry Pico (RP2040) for the brains and it took a lot of tedious bodge wiring to tiny via’s and smd pads. I’ve got all the panel functionality working except the rotary dial which countio in circuit python doesn’t seem to want to pick up, but I might have fried the PWM peripheral as I forgot the strip some of the existing 5v pull-ups.
And yes, I need to align the two SLG2016 LED displays.
7 Likes
Hey @danbass - This looks great, im a bit behind you on a very similar path. Did you get your own boards made for the AO modules?
General rule, if they are white faceplates, I got them directly from Rich, if they are black I got them made at JLC. Ive also had swaps with quite a few of the community members here.
I also have quite a few of his modules that either aren’t racked, are near completion, or are in the next wave of modules i hope to finish.
Does anyone have spares or want to get some? I’m interested in PCBs and Kosmo faceplates.
I’m happy to get some ordered, getting 5 feels inefficient if I only need one.
I thought i remembered a thread on that, but I can’t find it at the moment…
Your module could not come at a better circumstance as I just got a couple of UA776 from a reputable source! I know that people have modified slightly the circuit to make it work with NTE888M, but I assume that the MC1776 that you specify is a direct replacement just like UA776?
1 Like
You can trade/sell PCBs and related things here: https://lookmumnocomputer.discourse.group/t/the-bst-thread-buy-sell-trade/
3 Likes
Yes, I just dropped the MC1776s (and the other op-amp & transistor substitutions) directly into the filter without changing any of the other core component values and it works beautifully. Good luck with your build!
1 Like
Last time I quoted international shipping of modules, it didn’t make a lot of sense financially, but I bet there’s a larger contingent of kosmo folk around London. There are a few regulars here in the states that I’d reach out to if I was doing another run of modules to see if they wanted to split an order, perhaps you could use the forum to try to do the same around you?
1 Like
Hey smart people from this form… I got the GB color mostly working but the CPU mod is not working as intendet. the GB crashes the moment i turn the ltc1799mod on. I think i found the cuase of the error but the solution is beyond my abileties:
Classic (DMG) game boys run on 4mhz and Color (CGB) on 8.x mhz…
there is a formula in the GB oscillatro documentation to calculate the correct values but i can’t adapt it to my needs…
this is the circuit: (based on)
what is different than all the previous GB modules:
- GB color runs on 3V, LTC 1799 accepts that too, I changed the complete thing from 5V to 3V
- GB color runs on 8mhz
my guess is that the changed V-input and the required increased clock-range are causing my problems… i think i have to change R4 (1K) and RV1 (47K) to compensate… but i have no clue…
I do, but I’m in the states.
I got all of my projects up on my GitHub, feels awesome to have everything in one published place:
Also got the finished ones up on the Kosmo Wiki
5 Likes
I’m going to be in the US for work next week. Not enough time to order PCBs and bring the spares but if anyone has any spares available…
Something that could be useful for those who are thinking of ordering something and collecting it when they travel abroad. Most UPU country members allow people to collect mail without having a physical address. The international/French term is “POSTE RESTANTE”, while the US uses the term “GENERAL DELIVERY”. You just put that term and the address of the designated post office that accepts such mail instead of your home address, and you can collect it by showing your passport. Each country has its own rules (you need to check), but generally they will keep your mail for about two weeks. So if you plan well in advance, its doable (I have done this before, in different countries).
I ship stuff to my hotel, its always worked out - thats a good option though if you havent booked a hotel room or are unsure that they will cooperate.
Whenever I see a tutorial on programming the STM32 (e.g. the bluepill) aiming at DIY I see that people use the IDE by ST, which I think for a beginner is quite complicated. I mean, it works, but it has quite a bit of a learning curve. Also the code looks quite hardware specific. I wonder how many people program it using visual studio code (or some other IDE) and build their code base on what VSC calls the ‘arduino’ framework. If you have some experience programming an arduino in the arduino IDE using various libraries etc. then programming e.g. a bluepill is a breeze because you can do it in an ‘arduino style’. So you can use delay(), digitalWrite() etc etc in stead of complicated stuff like HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_1);. Switching from an arduino to a bluepill mid project also is easy when using this framework. You only need to change the board name (and platform = ststm32). I was forced to do so when I ran out of memory on a nano in a projecct and had to step up to a bluepill. Yet, I hardly see any use of that framework in tutorials. What do you use?