tempus fugit wrote:
"John Popelish" wrote in message
news
tempus fugit wrote:
Here's the schematic you were asking about John. This is the section
from my
amp that is used for remote switching. The original design was to have
the
'effects 1+2 footswitch' connected to a mechanical switch, but I wanted
to
change that to transistor switching so that I could incorporate it into
my
pedalboard.
Where is the LED you mentioned in your post to
sci,electronics.basics,

"Thanks for the reply John.
I'm switching 12v at the collector
with 5v at the base.
The 12v is coming through a 100K resistor
from the previous device, so the current
is pretty small.
I've found that using a standard (2N2222 type)
transistor doesn't quite switch things
all the way off
( there is an LED indicator
that still glows faintly)."

I am assuming that it is something you are adding at the
transistor switch replacement part. I also need to see the
schematic for all that, to understand what you are testing.

If you just wanted transistors to replace the mechanical
switches, they could easily be 2N7000 type mosfets or
something with even higher resistance, since they only
switch the 150 uA current through the 100k resistors in the
amp. The harder problem may be keeping the off state
leakage current well below something like 15 uA to let the
effect be all the way on. If the LED gets involved in this
current, it will easily interfere with such a high impedance
deal.
]

Woops. That schem isn't covering enough ground. Here's a bigger chunk. The
LEDs in question are marked 'Lead LED' and 'Rhy LED', and are part of the
amp itself, not my switching system.


Not there yet. The post at the top talks about the effects
1+2 foots witch, but the LEDs are connected to the channel
select foot switch. I need to see the experimental
transistor circuit you connected to this amp that didn't act
as you expected, so I can help you figure out how to fix it.

Did you just relocate the Q7 Q8 circuit to outside of the amp?