electronics for
dummies II
introduction to common electronic components 2
buddha machine hacking
reading schematics
circuit (1): simple oscillator
voltage regulators
higher voltage (e.g. 9V)
lower voltage at a constant value
transducers (speakers, piezo)
vibration
electrical signals
logic gates
true / false states
buddha machine hacking
a beautiful circuit-bent buddha machine I found on ebay...
procedures
unscrew & open up until you see an exposed circuit
board
look for the “clock” circuit: look for resistor +
capacitor pairs near the IC
wet your finger and touch around
when you have found a hotspot mark it on the circuit
board, use crocodile clips to test combination of
connection points
replace clock resistor with a pot
reading schematics
ground
schematics are abstraction of circuits
How to read schematics:
(1) - connections?
How to read schematics:
(2) - operational flow
input
output
How to read schematics:
(3) - identify parts
Resistor no. 1
How to read schematics:
(4) - identify values
A resistor of 10k ohm resistance
circuit (1): simple oscillator
Connect one side of the audio jack (sleeve) to 0V and the other side (tip) to the output
how components work together
!
9V in, 5V out
9V in, 5V out
logic
inverter
9V in, 5V out
logic
inverter
input and output of the logic
gate connected together, so the
value will oscillate between 5v
and 0v very quickly.
9V in, 5V out
The problem is that it
oscillates MUCH too fast to
generate a tone that is
audible. We are therefore
adding a resistor-capacitor
pair to slow it down with a
TIME CONSTANT.
logic
inverter
input and output of the logic
gate connected together, so the
value will oscillate between 5v
and 0v very quickly.
So what do we have here?
A square wave oscillator!
Duty Cycle Adjustment
Duty Cycle
The duty cycle of a square wave is how long
it spends at logic 1 vs. at logic 0.
For example, a wave that spends 1 ms at
+5V and 1ms at 0V per cycle would have a
50% duty cycle.
1.5 ms at +5V and 0.5 ms at 0V would be a
75% duty cycle.
When the input is high and the
output is low, current will be able
to flow through both
potentiometers, decreasing the
amount of time it takes to charge
the capacitor, and increasing the
duty cycle.
Variations
Insert a light sensor (light sensitive
resistor) to create a light sensing
synthesizer
Experiment with pots of higher/ lower
values
Experiment with caps of higher/ lower
values