Slow bit of progress, drilled up 8 panels. Chopped out some kosmo size blanks, installed a mixers faceplate and resoldered it to fit.
8 Likes
While I enjoy the standoff, I look forward to the build notes to see if a banana hanger was under consideration.
1 Like
Iām assuming thatās an off the shelf kit? Did you buffer or opto isolate the output? I built a kit with my Son but I havenāt been brave enough to connect the 5v output to my modular gearā¦
Which one? The Nuclear Decay module is my version of a TimMJN module:
which uses a commercially available Geiger counter and an auxiliary circuit to turn its output into a CV envelope. The Bong0 is a dual Kosmo conversion of an NLC drum module; I used the NLC circuit board (two of them) and just stuck them behind a Kosmo panel. Details on both forthcoming.
4 Likes
Very nice!
On the Bongos, what is the difference between āinā and ātriggerā? Isnāt the output always a short bongo sound, regardless of the length of the input trigger?
After opening the box of parts from Digi Key I was able to complete one of the Hero VCOs. It even seems to work correctly. I still have to tune it though.
Chris
8 Likes
A quick visit to a shop by my office andā¦ the slow blow 800mA fuse did the work just fine. Thanks @analogoutput!
3 Likes
I havenāt messed around with it very much. But yes, a square LFO into in will trigger the module. In fact it triggers on both the rising and falling edges. A triangle LFO wonāt trigger it. A square LFO or a clock pulse into trigger will trigger the module, but on the rising edge only. In any case, whether triggered with in or trigger, the amplitude of the in signal affects the pitch ā so with the square wave into in it alternates between high and low. But the pitch is unaffected by what goes into trigger.
1 Like
I know. Playing a rack synth can get rough at times. Sometimes you even break modules! Thatās modular for you.
" the-new-case-has-space-for-years-day " haha yeah thats what we tell ourselves every time .
4 Likes
Not even dog years.
4 Likes
I was working on the stand for my 2nd rack.
Combining the 3-D printed parts and some wood I connected it all together and added some of the 19-inch cases I use for my modules. I also re-purposed a left over aluminium module frontpanel to give the stand a bit more rigidity.
My vocoder consisting of 2 of those 19-inch cases will be stacked on top of the rack shown in the picture. And Iāve got some more 19-inch cases to put on top of those. The top bit will be curved to the front. The goal of this curvature is to make it possible to read the texts on the top, center and bottom modules while standing in front of the rack.
15 Likes
Wonderful design. Do you have a link to those 19" cases?
Thx.
I will put the STL and openscad files on my github later this week.
Iām in Europe and order mine from Gie-Tec in Germany.
They are cheaper than any seller of modular gear Iāve found so far.
You can find the 19-inch cases here: BaugruppentrƤger - Gie-Tec GmbH
B.t.w. I found this supplier because it is metioned as the source of rack material in some of the Doepfer documentation.
2 Likes
Almost finished a Kosmo adaptation of David Haillantās simple VCA. Before I put the LM13700 in the socket, however, I did a little measurement at the test points at the bottom of the PCB. Everything fine. I pop in the IC, turn on the power, all fine. I plug in an input, an output, then a CV inputā¦ I get a fuse blown. A change of fuse and another try. This time I wait a little before I plug in the CVā¦ and I smell of burning plastic. I turn off the power and I notice that the ceramic bypass capacitor at the negative supply of the IC has been damaged. Fake LM13700? I got them from āyou know whereā cheaply. I also got another one, not so cheaply, from a local shop. Any advice other than replacing the capacitor before I try the other IC that I have?
1 Like
What makes you suspect the LM from being fake? For a bypass capacitor to go bust the way you describe it is a rare thing in my experience. Maybe it had a short in it from the start. From what you describe there are no clues that the LM is the cause of any problems. The LM will not burn the bypass capacitor anyway. The fact that the power supply fried the capacitor tells me the power supply is working.
I would suggest you take the ICs off the board and start checking some voltages.
Have you checked the supply voltages on the IC pins? Are the plus and minus supply connected to the right pins? Next check for shorts using your multimeter ( disconnect power first ! ) across various components. Donāt forget to check the jacks !
Once you are confident to put the ICs back, try the module with a power supply you can choose the voltage from (positive and negative) and put an amp-meter in series with its outputs so you can measure the current to the module. Then slowly turn the voltage up and watch the amp meter. If the amp meter goes up too high very quickly, turn down the voltage and check for shorts or wrong component values. Remove the short and repeat the startup sequence.
2 Likes