DIY Project Show & Tell

[gene_stl]

not terribly high but very high voltage rating. Unless it arcs through

 

[quadsearcher]

A several KV capacitor.

My winning science fair 7th grade project was also from Pop Tronics but it was simply five or six games built from the writer's instructions. There was a two person reflex test/competion with a rolling metal ball on metal rails and a switch/gate. The idea was to be the first to press a button after the ball hit the gate. Sort of a primitive sample hold with trigger. My favorite was the eye/hand coordination test with a soft metal bendable rod into hill and valley shapes with a metal loop one would navigate along it without hitting the rod.

 

[gene_stl]

I built a two tube "phono oscillator" which was a little am band transmitter you could plug a record player or microphone into and have it come out of a nearby AM radio. The two tubes did not include the power supply which was furnished by my science teacher. I was trying to determine if Radio waves obeyed the inverse square law. I was in the ninth grade. I got an A from the science teacher but it took too long to actually make it to the science fair. The circuit came from a library book on electronics. I bent a chasis in shop class. Somewhere I got ahold of greenlee punches for the tube sockets. The shop teacher helped me with the sheet metal work (sheet lunimum) and I was very happy with the way it turned out. The power supplies I used belonged to the ninth grade science teachers room. I have tried to find the circuit I used online but have not had any luck. It had a 6V6 and a 6SN7.

I also built the Pop Tronics Lumemin (page 14)
https://www.worldradiohistory.com/A...ectronic-Experimenters-Handbook-1966-Fall.pdfIt worked perfectly but was extremely difficult to play. I sold it to a guy at the "Ludwig Aeolian" Piano and Organ store. He must have been in a band and wanted to play "Good Vibrations" and similar songs. He was very happy to have it and I was happy to "escape with my skin" This time I used a professionally made chasis which had a hammermill paint finish. It turned out very nicely. I think I was a sophomore by this time. But I was an old hand having taken an electronics summer school class where you wired stuff with Fahnestock clips and got shocks from tube power supplies (probably before ninth grade) and had gotten interested in electronics in the fifth grade. So by the time I got interested in audio (Freshman year of college 1968) I was kind of an old hand. We also had a terrific electronic surplus store here in St. Louis which COVID delivered the coup de grace to.


Then came Dynakits, Heathkits, Southwest Tech Products kits and various technician jobs.

 

[LB-V]

I still have the magazine!

I'll be darn!

 

[LB-V]

Duplicate - delete

 

[bob.stek]

I won an honorable mention at the 1965 Rutgers science fair for F.R.E.D. - feedback regulated electronic device - based upon a Pop Electronics article for a contrast following 'robot' which used light reflected on a photocell from black tape on a white background (or white on black) alternating power to a left or right wheel motor. I focused on the notion of feedback controlling a device. Later, as a psychologist, I got into muscle and brainwave biofeedback professionally. A previous article in Pop Elec about radio signals from Jupiter led to me creating a hoax about Jovians hiding in a swampy area in my backyard!

 

[barfle]

Amy estimate what the Farad rating might be for a capacitor like that?

Nothing with any precision. I know there are formulas for calculating the capacitance from the area of the conductors, the distance between them and the dielectric constant of the insulator. FWIW, I recall there being four interleaved plates of about 1 foot square and the plate glass being about 1/4” thick.

 

[gene_stl]

I remember the strip following robot. It was interesting but would have been spensive for a high school kid to build. Interestingly much later I built a little kit of exactly that for my now 46 year old kid. It was bought at the aforementioned electronics surplus place for about $20 in the late eighties. It had a nice plastic chasis and a clear dome covering it four or five inches in diameter. All the parts in a bag and it went together easy and worked fine.
Progress.

 

[barfle]

Digging through my computer's documents folders, I ran across this article from "Popular Electronics."

While I'm sure there are better decoders available, if you're really interested in something like this, well, there's this:

 

[MidiMagic]

I am a real do-it-yourselfer (until recently when my age has caught up to me). Here is a partial list of things I have built:
- A neon sign made of NE-51 bulbs that flashed to music sent through an amp and transformer (still have).
- Two color organs, one analog and one digital (still have both).
- An overhead projector (Edmund Scientific kit - still have)
- A Hafler diamond decoder for RCA connected speakers, and a 6-channel version.
- My UQ-1 passive quadraphonic decoder (Plays Scheiber, EV, DQ, QS QM, and DS.

My 4-channel direction-vector-oriented oscilloscope display

- My UQ-44 passive RM/SQ decoder (on my website)
- My encoder attachment for any 4-bus audio mixer:

Put it in the bus insert for bus3/4
Here's how to use it:

- Traffic actuated hallway lights (made with motion detectors).
- A flat spectrum light made with LED bulbs.
- This modified record changer (still in use):

I added the following features:
- Smoother running motor and bearings
- Better arm bearings
- Mount for Shure M44-E
- Antiskate
- Pitch control
- Cue control
- Take-away overarm for 45s and manual use
- Increased size measurement range
- Ability to play very small records.
- Full manual start
- Turntable stops during change cycle so records do not slip
- Automatic speed change (large 33 followed by small 45 - see image)

Continued next post

 

[MidiMagic]

I am a real do-it-yourselfer (until recently when my age has caught up to me). Here is a partial list of things I have built (continued from last post):

Early Projects
- Built a vertical-take-off rubber band powered airplane at age 10.
- Built a working model of a GM Hydramatic automatic transmission at age 12.
- Built a model stage with a working stage lighting system at age 14.
- I made what I believe to be the first live theater set of sound-effects cues using the Hafler diamond. It was used in live theater in 02/1971.

Intermediate Projects
- Added passive matrix varying to the UQ-1 making the UQ-1V

It uses the non-ohmic properties of a lightbulb to reduce back separation when a strong front center signal is present.

- Modified a pinball machine to use and keep track of two balls instead of one (Predecessor to the Multiball series).

Recent Projects:
- Added second gear start to my Pontiac Bonneville for winter driving (I no longer have the car - I used this for 7 years).

--- The red switch turns on second gear start.
--- The white light at left on the round display at top shows second gear start is active.
--- The right light shows what gear the transmission has selected.
----- off = 1st, red = 2nd, yellow = 3rd, green = 4th

- Built a two-thermostat system for a furnace that notices when the floor is cold.
- Made a vernier analog thermostat that holds settings.

Made a switchbox that can put up to 4 lamps in any series connection or any parallel connection by throwing switches.

Built a switchbox to select different quadraphonic matrix systems for an array of 10 speakers:

. . . .

Invented the first fully fair voting system: Independent Voting

You can vote any selection on any candidate position including abstaining (doing nothing).
The candidate's score is total yes-votes minus total no-votes.
Highest positive score wins.

- Wrote a webpage to calculate traffic signal progression (makes lights turn green when a platoon of cars comes to them)