Pyramid
1980's
(click to enlarge)
This is an electronic art piece made in the early 1980's inspired by a
sound only version in a local art gallery. This has a variety of
circuits to flash the 50 or so LEDs in
various ways. There are 3 mercury switches to sense the position of the
pyramid which can be tipped with any of the 3 apices up with different
results. It turns on in response to decreasing ambient light intensity
hence will turn on as you approach. The actual light intensity controls
the flash rate. It 'plays' electronic sounds and also has a door bell
chime chip to play 24 tunes in sequence as one of the options. There are
no printed circuit boards and all wiring is point to point and supported
by the inner and outer pyramids which are also the supply rails.
A
whatchyamacallit 1980's Not sure what to call
this thing made about 20 years ago.
(click to enlarge)
It used some sort of transistor oscillator (now covered in tape) driving
an E core iron electromagnet at >20 kHz. It runs from a small 9 V
battery and has a reed switch in it to turn on. You bring the box of
matches with a hidden magnet just visible here close to turn it on. It
induces a current in the coil of unknown turns to drive two LED's on a
smiley face. The LED's still light up about an inch away. It still works but I have replaced the LED's after the
leads broke and replaced some of the tape. So, remote signalling
and remote power transfer 1980 style!
Peltier effect device (thermo-electric cooler) These are
semiconductor heat pumps that use electrical energy to cool one side and
heat the other. This 100W device runs on 15V 6A or so and are
meant to cool Pentium like processors. It requires a good
heat sink to get rid of the heat and preferably fan cooled. There
is an optional controller to fix the temperature between 30 - 40 C.
(click to enlarge)
On the left picture, ice is forming on the top plate while the
fan-cooled heatsink is getting hot as it has to handle the 100 W input
plus about 50W of heat pumped away from the top plate. The right
picture shows a smaller Peltier device from inside a laser component
which I have mounted on a small heatsink and fan.
(click to enlarge)
Peltier devices can be used in reverse to generate a voltage from a
temperature difference. Here is the 100W Peltier device generating
126.6 mA at 359.3 mV which is a total of 45 mW. I have poured
liquid nitrogen on to the top surface.
Medication delivery device (AutoDose)
1990
(click to enlarge)
This is a device
I made in 1990 for use by elderly forgetful patients who may not
remember medication times. In essence it is preloaded with one weeks
medications. The internal timers then rotate the platter such that the
medications are visible to be taken. A light flashes and buzzer sounds
until the medications are removed (triggering an infrared beam). It has
an internal rechargeable battery which can last a week if unplugged.
There are safety interlocks. The most complicated part was designing a
programmable timer for up to 4 medications times from scratch using
discrete parts.
Digital voltmeter / frequency meter
1980's
(click to enlarge)
A combination of two kit projects crammed in a small case made in the
1980's.
Hi-Fi power amplifier
1990
(click to enlarge)
This
was fan cooled and rated at 100 W/channel into 8 ohms. It was used
in my Honda Civic for many years running from a 300 W 12 V / 240 V inverter.
It powered a set of efficient large Cerwin Vega speakers with 12 inch
woofers which took up all the space behind the front seats.
