MOTM

Anyone still have the pix of this mod, below link is bad.
Cheers
Jim

Dave Bradley wrote:

> Well, it's kinda boring on the list, time to stir things up a little..
>
> I've been threatening to do this for a long time, but I finally had the
> time - I modded my MOTM 800s to have an output LED (yes, Barlow, you were
> right, it's cooler than a gate LED.) It glows in brightness corresponding to
> the level of the envelope output. It gives you immediate feedback on what
> your envelope generators are doing in the midst of a complex patch, and
> helps to troubleshoot when things are not being gated correctly.
>
> Pix at:
> http://www.egroups.com/files/motm/800mod/
>
> It's an extremely simple circuit consisting of 1 dual opamp , 1 LED, and 1
> resistor. This circuit also could be used most anywhere else you needed a
> visual indicator of the signal level. For bipolar signals, you'd maybe want
> to use a bicolor LED as in the 320. In addition, you need to mount a small
> daughterboard on 2 threaded standoffs, screwed into the embedded studs
> behind the front panel.
>
> As usual, I accept no responsibility if you fry anything, burn down your
> house, scorch your cat, etc. This is about as easy as DIY gets, but you can
> make mistakes, and short power supply rails if you're not careful. Paul will
> want me to mention that if you start adding lots of LEDs to your system,
> make sure your power supply can handle the extra load.
>
> Referring to the schemo (see the pix link above), the first half of the
> opamp buffers the signal, the second provides a current driver to power the
> LED. The 470 ohm resistor sets the max current to a little less than 10 mA
> for a +5 volt input. You can connect the input to the OUT + jack to get an
> output indicator that varies in intensity with the envelope, or to the GATE
> jack to get a simple gate indicator. Note that if you are using it as an
> output indicator, and you have nothing plugged into the gate or trigger
> jack, the LED will glow. This is a good reminder that the 800 does in fact
> send its DC sustain level when not connected otherwise.
>
> Notes:
> Dual opamp - almost anything will do, as long as it can sink 10mA. I used a
> crummy old 1458 I had laying around, and it was plenty fast enough.
>
> LED - I chose green since MOTM-320s use green to display the amplitude of
> the signal when in a positive range. Use the Lumex part to match the MOTM
> standard (GREEN:Digikey # = 67-1156-ND,Lumex number = SSI-LXH387GD). If you
> can't deal with DigiKey, maybe Paul will sell you some.
>
> Standoffs: Use 6-32 threaded aluminum standoffs, 5/16" long works well.
> Remove the KEPs nut, put on a small flat washer and lock washer, then the
> standoff.
>
> Daughterboard: I went to Radio Slack, bought their protoboard, and sawed it
> into strips. I got enough to do 4 800s. I mounted the board copper side up,
> components underneath, so that I could bring the LED leads all the way
> through the daughterboard when mounted, and still solder on top where I
> could reach. Power for the opamp is brought from the back side of the main
> board power connector. Be careful you don't short anything.
>
> Enjoy!
>
> Moe "gimme an LED!"
>