Odp: [sdiy] Keyboard encoder and DA

[Roman]

MC1408 has current output.

If it's DIP package the pins are:
5-12 data input
13,14   +5V
1,2,15  GND
3    -15V (-10)
4    2.5k resistor to ground - this is your voltage output
16    47p cap to pin 3 or GND

instead of resistor at pin 4 you can connect an opamp (inverting input) with
2.5k resistor acros its output and inverting input. Opamps noninverting input
tied to GND. Then you'd have positive voltage output instead of negative like
with resistor only.

get a datasheet. It's all there

Roman

----- Original Message -----
From: Karl Ekdahl <_nial_ at yahoo.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Monday, October 07, 2002 5:26 PM
Subject: [sdiy] Keyboard encoder and DA


> Hello everyone.
>
> I'm nearly finnished with my keyboard encoder, but i'm
> stuck again. I can't seem to get that !"#¤% D/A to
> work. I'm using a MC1408 and it seems pretty easy to
> get it going, but of course i can't. Is the MC1408
> giving a current output or voltage? I suppose current,
> how do i convert this current to a control voltage?
> Can anyone just give me a hint on how to build a tiny,
> tiny test circuit so i could see the MC1408 live at
> all? I've tried several designs, and several MC1408:s
> (since i thought that maybe i'd burned them) but
> nothing works for me.
>
> Hmm...   ..maybe this is to advanced for me, i better
> drop this and start building LEGO again.
>
> btw. the former 74373 problem i had was because of a
> bad-quailty data sheet...
>
> /Karl
>
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