1V/Oct. Keyboard Controller Question

cea-six · Joined: Dec 08, 2010 Posts: 7 Location: 210

is it possible to use up to 61 keys????

cea-six · Joined: Dec 08, 2010 Posts: 7 Location: 210

oh and where dose the other end of the KBUS rail get connected to. meaning one end connected to the KBUS and the other end is connected to...?????

blue hell · Posted: Thu Dec 09, 2010 8:40 am Post subject:

Please do not double post - I've removed that other message. When you think you could formulate a question better you can always edit your original one; there is an edit button on the right side above each message you posted.

Do you have a link for me to the schematics? I could have a look then.

cea-six · Joined: Dec 08, 2010 Posts: 7 Location: 210

sorry about that i couldnt see my post in the forum so figured i didnt submit it. but as for the schmatic its the MFOS 1v/oct keyboard controller project. http://www.musicfromouterspace.com/analogsynth/SINGLEBUSSKEYBOARD2007/SINGLEBUSSKEYBOARD2007.php

thanks for looking

blue hell · Posted: Thu Dec 09, 2010 12:50 pm Post subject:

ok .. 0.833 mA over 61 * 100 + 475 -> 0.833 * 6575 .. about 5.5 V and also about 0.833 * 5 k .. about 4.2 V or about 9.7 V in total ... leaving 12 - 9.7 = 2.3 V over Q1 .. seems a bit low ... but on 15 V I reckon it should work with 61 keys.

The other end of KBUS is connected to nothing when you do not press any keys .. once you press a key though it gets connected to on of the resistors in the chain.

cea-six · Joined: Dec 08, 2010 Posts: 7 Location: 210

thanks again i really appreciate it

willi · Joined: Oct 20, 2008 Posts: 13 Location: Portland, Oregon

Blue Hell, would you mind expanding upon the calculations you show above? What are you computing? Thank you!

blue hell · Posted: Sun Dec 19, 2010 2:41 pm Post subject:

Was trying to calculate the voltage over the current source and over the resistor chain to see how much head room there is for the current source to maintain a constant current.