General > General Technical Chat
What was your first circuit? Do you still remember it?
jonovid:
the two transistor flip flop circuit & before that, a torch circuit on a block of wood
Electroplated:
First electrical circuit, battery and bulb featured in a Janet and John kids book when I was 6 years old, first electronic circuit, way back in 1964, a EL84 (iirc) valve amp and output transformer from a scrap radiogram, had a photograph of it until a few years ago, was also my first introduction to the theory of electrocution and why valve HT is derived from a transformer and not a direct feed of 230v mains :)
RJSV:
Electrocution is over-rated. NOT.
Somewhere there, 5th grade at 10 years old, figured out you could hook toy train transformer 10 vac output to another toy train transformer, 'backwards', into the 10 volt terminals, that generates voltage back up at 120 vac.
Problem happened right away, when I GRABBED the wires, clumsy, and got shocked, through the hand.
Lucky, maybe simply due to no ground path, but it would definitely have caused internal burns...very serious (potentially), but I let go fast.
brucehoult:
--- Quote from: RJHayward on November 08, 2022, 10:09:22 pm --- Electrocution is over-rated. NOT.
Somewhere there, 5th grade at 10 years old, figured out you could hook toy train transformer 10 vac output to another toy train transformer, 'backwards', into the 10 volt terminals, that generates voltage back up at 120 vac.
Problem happened right away, when I GRABBED the wires, clumsy, and got shocked, through the hand.
Lucky, maybe simply due to no ground path, but it would definitely have caused internal burns...very serious (potentially), but I let go fast.
--- End quote ---
A 600V+ mains supply can pump 4A through the body, causing severe internal burns.
A 1960s Hornby train transformer puts out about 2A at 12-14 VAC. If you use a second identical one to convert back to to 120 V then you're going to have no more than 200 mA (or 100 mA for 240 V) through a short circuit, and a less through a human body. That's a huge difference to grabbing mains directly.
themadhippy:
--- Quote --- Somewhere there, 5th grade at 10 years old, figured out you could hook toy train transformer 10 vac output to another toy train transformer, 'backwards', into the 10 volt terminals, that generates voltage back up at 120 vac.
--- End quote ---
At around 8 i discovered a mechano set motor in series with the secondary of a bell transformer produced similar results,and was portable so could be used in the school playground.Another early project was the sweary box,4 7 segment displays,a rotary switch and a load of diodes,turn the switch and varies swear words would appear on the display.
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