[sdiy] DC Offset Injector?

[Oren Leavitt]

Hi Joe,

Best if you make an active summer with an op-amp.
The passive mixer will vary too much with load impedance.

Oren

-----Original Message-----
From: Joe Kramer <musetrap at earthlink.net>
Sent: Mar 17, 2004 4:11 PM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] DC Offset Injector?

Hi Friends,

My MS20 LFO generates a +/- 2.5v triangle wave, and this is fine for most
of the internally patched functions.  But once you start patching out, there is
an obvious need for a zero-to-5v wave, for instance when modulating one
VCO against the ring modulator.

Can I make a passive DC offset injector with, say, 10k resistors and
pots and a power source--basically a mixer with the LFO as one input and
a DC voltage as the other input?  If so, is 10k a safe all-around value?

Or do I have to use an amplifier to do this?

Thanks,
Joe