Posting Permission

If anyone who wants posting permission on this site please email me and i will add you



Thursday, February 12, 2009

Some Photos From Feb 8th

Here are some photos of the Feb 8th meeting.

Tuesday, February 10, 2009

Optical Synthesizer Documentation

This post will contain all documentation relating to the optical synthesizer project.

The schematic, layout and the whiteboard hardware wiring description are available here.

There is one item missing from the whiteboard list. The black lead coming off the battery snap should go to the "G" terminal on the DC Jack.

I have added some hints on how to make the probe assemblies for those that are not that far along. Same location, "MakeProbesOne" and "MakeProbesTwo".

Obscene Fuzz Documentation

This post contains all documentation related to the fuzz project.

Schematic, layout and hardware wiring diagrams available here.

Note 1: i have made a very slight revision to this design which involves adding one more capacitor. Both schematics are available at the above link.

Note 2: leds could be used instead of 1n914's to increase the maximum output level or replace 1 1n914 with 2 in series etc...

There are now more sound samples available here and i also have a few available for sale for $35.

Sunday, February 8, 2009

Trouble Shooting...


Here are some specific insights into the synthesizer board.

1) Jacks

First check that you have the output in the correct jack. Remember we called one TRS and one NC-TS. The TRS is the output. There does not have to be anythign connected to the NC-TS for the unit to operate.

2) Voltages

Here are some DC measurements you should find on the ICS.


The pic is the MIDDLE IC.

Pin 1 of the MCU (PIC12F683) Should have 5 volts. If you are measuring something higher disconnect power immediately. Verify that R18 is installed correctly and that the Zener Diode D2 is oriented in the correct position. One side of R18 should show 9 volts and the other 5 volts.

Pin 8 of the MCU is ground. All other pins may vary during operation.


This is the op amp labeled TLC272 on your handout. Im not sure why it dosnt say 2272. Pin 8 should show 9 volts. Pin 4, 5, 6 and 7 should show 0 volts. Pin 3 should show around 2.1 volts.


This one is labeled TL072 on the layout.... Pin 8 is 9 volts. Pin 4 should show 0 volts. Pin 3 and 5 should show around 4.5 volts.

3) General Signal Flow

If you have an oscilloscope you can try to follow the signal incase it is being generated but not making it through the volume modulation.

Power on the instrument and hit the red button once to advance it into the sound generating subroutine. measure the output of pin 5 6 or 7. you should see square waves with 5v peak to peak. If you dont see any output on any of these pins keep depressing the red button and measuring. If no signal is obtained there is a flaw with the mcu itself.

If you see some squares there move on to pin 7 of the RC4580. The output of this should show (with some DC offset) a signal of somethign in the order of 2 volts peak to peak. If you see nothing on your screen make sure you have compensated for the dc offset either by adjusting the vertical position or switching to AC coupling.

Still nothing? there is problem with this op amp. Double check the power on the pins mentioned above.

If you have something on pin 7 check on the tip of the NC TS, you should see the same thing there. And accordingly on the switch side of the NC TS.

Now check the output of the 4580 on pin 1. If you have something here but no output on the jack then double check that you have "out" on the pcb wired to the TIP of the TRS.

4) Probe Response

my probes do nothing

Disconnect the probe assembly from the unit. Set your multimeter to a 200k or 2M ohm range. You may have to remove the hood from the connector to verify you are measuring the correct pins, but in general you should read a resistance that varies from about 500 ohms to over 100k across the red and black wire pairs. ie the resistance across each probe should vary when it is exposed to light. If the resistance is infinite or you measure open circuit and see no variation then either there is a disconnect at the photocell or a broken connection at the plug. Make sure the black and red wires are securely soldered onto the plug pins by gently tugging them. If you measure a very low resistance that dosnt vary then the red and black wires are shorting somewhere.

the change in response caused by the pots is radical, abrupt and does not vary over the whole rotation of the pot

De solder the wire on the two outer pins of the pot and exchange them. ie the wire that was going to the left side now goes to right and vice versa.

I will add more later. Please post in reply or email me if you have specific questions.

Sunday, January 18, 2009

Specifics of Jan25/Feb8

The address for the workshop is 5832 Blvd St Laurent.

The time of the sessions will run from 5-9 pm on both Jan 25th and Feb 8th.

If you have a soldering iron/wire snips/strippers/needlenose pliers please bring them along. (If you dont have, dont worry).

Please feel free to bring some music/munchables as well.

email if you have questions

Saturday, January 3, 2009

Details of next workshop Jan 25th 2009


So there will be another workshop on January 25th (which is a sunday). It will be in a space in the mile end area.

More importantly here's what i am offering up. The main project is something like an optically (light) controlled synth. I tried to push it a bit further then the somewhat limited 555 synths that are all over the place. I put some videos up so you can see. Right now i have about 5 or 6 sounds programmed in but i am working on more now that everything is functioning well otherwise. So please take look at the vids. There is a dynamic sensor (volume) and a pitch sensor. The sensitivity of each probe is adjustable via 2 pots. Then there is a button which may be hard to see in the first video but it cycles through the different sounds. (dont worry you get a case, i just haven't put mine in one yet)

I will also offer a very simple project with few parts that is an extremely fuzzy distortion. I made a short clip of one i made, you cannot see the board in the video but there is only 10 or 12 parts on it. It would be a good project if you just want to get your feet wet.

The synth project is $50 and the fuzz is $40 for everything you need. If you would like to participate i need to receive confirmation asap and payment by January 16th at the latest. Im arranging a second date as well which will likely be feb 8th (exactly 2 weeks later) so that you dont have to rush to finish in one day.

In terms of tools i have some extra soldering irons and some other basic things so if you dont have much/any dont worry there will be something available, but please try to bring your own if you do have them.

Also, if you have come to a previous workshop but you are not finished/you are missing or have lost parts etc... please feel free to come to this and finish up but please let me know in advance what you need or where your at.

You can contact me at