■ FIGURE 3.
■ FIGURE 4.
• 484 lower sideband Fo =
• 484 upper sideband and 494 lower
sideband Fo = 497.2 kHz
• 494 upper sideband Fo =
equivalent to the MOSFET that I used
22 April 2013
The coil Q has to be high —
above 50 and preferably 100; if it is
not, you may need to adjust the
resistor values to compensate.
I started with a stagger tuned
filter but did not want to use that
many tubes (or transistors), so I
converted it to a top coupled design
by fiddle and fudge.
A pentode tube should be
A PUSH ON/PUSH OFF
CIRCUIT THAT WORKS
QI have a Christmas music ircuit with an existing push on/off (momentary contact) which I attempted to use to
repair a snowman. I ended up using
a slide switch and just energizing the
circuit as needed. I still question why
the transistor circuit would not have
I built this circuit with
RadioShack 2N4401 and 2N4403
transistors. It worked only in that
SW1 would start the circuit. Shorting
it again would not stop the circuit.
Shorting the junction R3, R6, and R7
to ground would turn the circuit off.
The demo for it on You Tube showed
the circuit working with a .1 cap
between the output and + 9 volts
which was the author’s fix for
instability in the circuit.
Send any questions
and/or comments to: