a small single sparkplug ignition coil.
The primary winding is 1.9 ohms and
Re: Remote Tester Problem,
March 2013, page 21.
Any cell phone and most digital
cameras will detect the emission from
IR remote controls. Since most of us
have cell phone cameras (try to buy
one without!) or some type of digital
camera, these work well for verifying
the output of an IR remote control.
My 14 year old grandson clued me in
I tried it with my cell phone
camera and it works; thanks for the
the secondary is 7.24K. The circuit is
powered with a 12 volt, five amp
Basically, I used an NTE4584B
hex inverter; the first two inverter
logic gates along with D1, D2, C2,
VR1, and VR2 produce a square
wave with an adjustable duty cycle
The remaining gates are used to
amplify the signal. Q1 (2N3904NPN)
and Q2 (MJ2955 PNP) are set up as
a Sziklai pair to supply the negative
side of the ignition coil to ground. I
tried to block any EMF with C4 (R3
as a snubber), and D3 and D4.
On a USB oscilloscope, I get a
square wave between the outputs of
the hex inverter (pins 6, 8, 10, 12)
and ground. The signal is
approximately 25% to 75% duty
cycle, and frequency adjustment is
between 5. 5 kHz and 16 kHz. I’m
getting an inverted signal at Q2.