tag:blogger.com,1999:blog-23217409.post457759126826659404..comments2024-03-15T15:10:58.249+10:30Comments on little-scale: Monophonic USB MIDI to CV Converter with 8 Octave RangeSebastian Tomczakhttp://www.blogger.com/profile/12712567577323498804noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-23217409.post-51215675829819804082019-01-07T09:22:07.635+10:302019-01-07T09:22:07.635+10:30Great ideas all round, thanks for sharing! That is...Great ideas all round, thanks for sharing! That is great news that the ATtiny 85 can act as a USB device, awesome! I will have to check that out. Good idea on the trim pot too. Sebastian Tomczakhttps://www.blogger.com/profile/12712567577323498804noreply@blogger.comtag:blogger.com,1999:blog-23217409.post-39396330863550854962018-12-26T15:32:48.029+10:302018-12-26T15:32:48.029+10:30Love this post, Seb. I have done some modificatio...Love this post, Seb. I have done some modifications for my own purposes and combined it with ideas from DSP Synth's USB MIDI2CV project and stuffed it all into a 1U tile module. <br />The changes I chose to make was to use an ATtiny85 instead of a Teensy to help with size, cost and to remove unneeded parts. The other changes I made include a capacitor in parallel to R2 and R4 at about 680pF to function as a low pass filter for very high frequencies (above 23kHz). Another change I made was made R2 into 10k Ohms and R1 into a 15-turn 10k trimmer (turned to 5k) so very precise adjustments can be made to compensate for the 1% accuracy of R2. I also added a resistor in series to the non-inverting inputs of each op amp. The value of these resistors is the parallel value of R1//R2 and R3//R4 respectively. (So roughly 3k3 and 5k). These are to compensate for bias current voltage drops in the divider network. These two changes can stop the op amp from oscillating on its own in some cases. And lastly I have added a single npn transistor buffer to the gate output to grant it a touch more current if the receiving devices need it. <br />I separated DGND and ANGD too! ;)Fox Burroughsnoreply@blogger.com