HowTo Index: Circuits
To avoid unnecessary work and to help keep the diagrams up to date,
many of the more complicated circuits will have small block diagrams
referencing one of the other circuits listed here (think building blocks).
This also helps keep drawing cleaner and more easy to understand and
Some of these circuits have been tested more than others. Many pieces
are shown for learning and clarity.
- Simple Transistor Checker (N-Type)
- Project: IR Remote Control Repadding
- Project: IR Receiver, LIRC compatible serial type
- Project: IR
Transmitter (off the lirc.org site). I modified this by removing the
22ohm resistor (brighter IR output), replacing 0.5k ohm resistor and
regular LED with another single IR LED (for 3 IR LED's total in series),
and using a 2200uF capacitor instead of the 4000uF (because I didn't have
the bigger one handy). I can easily parallel another capacitor if needed,
but the unit works ok in my room. I also built this circuit without a
proto board and just wired all the parts around the large capacitor. From
there I mounted it in a vitamin bottle and drilled 3 holes in the lid to
mount the LED's each at a different angle for maximum dispersion. I ran
into a problem of my PNP transistor being bad (it was salvaged from
another project). I ended up temporarily replacing the IR LED's with a
single color LED for simple testing. If the color LED stays on constantly,
check your PNP transistor.
- Electronic Stethoscope
- Box Fan Wind Turbine
- Fuzzy Line 1: DC with
ripples on it (bad). In audio applications this can translate into
- Fuzzy Line 2: close up.
- AC1: Normal AC power wave.
- AC2: Close up of normal AC power
- Diode Bridge: Half. This is
what happens when only 2 diodes are used on a full AC wave. This came from
a cheap electric screw driver "battery charger"...if you'd call it that.
- Diode Bridge: Full. This is
what happens when a full diode bridge is used on a full AC wave. Keep in
mind that just rectifing an AC wave doesn't turn it into flat DC power. A
big capacitor is needed after the bridge.
- Diode Bridge: Full. Close
- Diode Bridge: Full
with 0.1uF film bypass capacitors. There's one capacitor across each
diode (4 total). The capacitors help smooth out the dips and silence some
of the diode switching harmonics. This makes it a bit easier for the big
capacitor after the bridge to turn AC into smoother DC. Note the complex
wave form from the push-pull effect of the capacitor charge/discharges.
- Diode Bridge: Full
with 0.1uF film bypass capacitors. Close up version.
- low voltage cut off: ?electronics book zeners p46, p103, p109, p113