(m.m.j.meijer@zonnet.nl)
Today I finished the SC3 B/W
mod to a Vesta 680. As the amp glow was
Anyway, I had no small relay
and wanted to try the last pin to test the standard SC1/2 amp-off mod. When
attaching the NPN transistor as a switch between pin 7 of the ICX424AL and pad 6
of the Vesta it worked. See the
attached image for the schematic, and two darkframes (60 seconds, 100% gain,
other settings at 50% and whitebalance: outdoor)
The parts I used were a BC548 transistor, a small 100nF capacitor (from an old computer board, where it was soldered between VDD and VCC of an IC) and a resistor of about 500 Ohm (may be less for a ToUcam, as it is less in the SC1/2 mod).
Circuit here
As far as noise goes: I have
not noticed any extra noise with this amp-off mod. The camera is a bit more
sensitive to noise than a normal Vesta, but that is because the CCD is placed 2
cm from the Vesta CCD board, to allow for cooling. And this noise is mostly
visible at 15-30 frames per second, and who needs this when doing long
exposures?
Regards,
Matthias Meijer
Amp
On
Amp
off
Hi Steve,
Today I did some measurements on the amp-off mod.
I used the following setup:
·
BC548 NPN with the collector connected to pin 7 of the ICX424AL
and the emitter connected to pad 6 of the Vesta CCD board.
·
a 560 Ohm resistor between the collector and emitter
·
a 100nF capacitor between the collector and emitter
·
the base of the transistor was connected to the parallel port in
the same way as for the SC1/2 mod (with the 220 Ohm resistor between the
parallel port and the base, and the 10k Ohm resistor from the base to 5V)
I
measured a voltage drop of 2.75V over the resistor when operating the camera in
the amp-off mode in K3CCDTools.
See also the attached photo’s for more detail on how I
made the SC3 mod.
Or should we now call it the SC3.5 mod??
I hope that this is enough information for you at this
moment.
Regards,
Matthias Meijer