[UPDATE] Please download REV2.1 zip file for the REV2 PCBs. I corrected some minor mistakes.
Changed the LED resistor with 470R one for a brighter LED switch.
https://www.dropbox.com/s/figy2dwut61yy ... 1.zip?dl=0
REV2.0 PCBs, have the following changes :
- I added a transistor buffer for the gate led (from the switch). Now the led have the same intensity on both 5v or 10v gate signals.
The led is not powered from the gate voltage anymore, so there is no load on the gate voltage.
- I added 74HC541N octal buffer between the SRAMs and TAP Switches.
- Grounded some gates of CD4049s, for a better stability.
These changes does not affect the 1BIT Delay sound. Nothing was wrong with the previous version.
I just checked again if I can do some improvements of the circuit.
1BIT Multitap Delay is an adaptation of classic 1bit delays from the 80s to eurorack with many interesting add-ons.
As the name states this module is a digital delay with 1BIT AD/DA and no CPU inside, similar in design with old delays like : Ursa Major, ADA and Effectron.
Even if it's digital, the module have a warm sound with analog BBD feel, but without the high loss on long delay times.
With two independent taps and outputs you can play with those classic running arps.
For example you can have a long delay on the TAP1 output, using x8 setup, and synced short delay on the TAP2 output, using x4 setup.
You can listen both taps on the mix output, or you can put them in stereo with independent outputs. You have a nice stereo effect even if you use x8 taps on both outputs.
The maximum time is 750ms-800ms. I calibrated the module in a way you can obtain dirty long delay sounds, so you can also use the module in the noise area.
With the LOOP functions you can freeze the sound, obtaining nice crazy effects. Also you can do that in sync with a gate in input.
The module uses 64K old school srams to delay the sound.
The DIY project will need 8 x 4164 64K memories, widely available on ebay. They were used a lot in old computers like commodore, spectrum, also in all the delays of the era, so a big stock of them still exists.
ATTENTION! AFTER BUYING LARGE QUANTITIES OF MEMORY CHIPS, I DISCOVERED 20-25% OF THEM ARE NOISY, DAMAGED OR NONFUNCTIONING.
I RECOMMEND YOU TO ORDER 15-20PCS. OF THEM AND CHOOSE THE WORKING ONES AS EXPLAINED IN THE MANUAL.
(this is common for all the different lots I purchased, it's depending on how they were stored, handled, electrostatic discharges etc.)
There are 3 types of kit available on my website :
KIT1 : 3 x PCBs + Front Panel
KIT2 : 3 x PCBs + Front Panel, 8 x 4164 SRAM Chips (tested)
KIT3 : 3 x PCBs + Front Panel, 8 x 4164 SRAM Chips (tested)
8 x Minijack sockets, 2 x 8 pos switches, 1 x Momentary push switch
7 x 10KB 9mm pots, 3 x 50KA 9mm pots, 1 x 100KB 9mm pot, 1 x 500KB 9mm pots, 11 X Cream Knobs 1900h type, 3 x Big Cream Knob 1510 type
3 x 3 way header MALE, 3 x 3 way header FEMALE, 2 x 6 way header MALE, 2 x 6 way header FEMALE, 3 x 14 way header MALE, 3 x 14 way header FEMALE
Thank you Future Music Magazine and DivKid for this really well explained video :
Also ColorMySound
https://soundcloud.com/strat1/1bitdelay-synth
https://soundcloud.com/strat1/1bitdelay-drums
