I wouldn’t worry about the solder; he’s not going to be sucking on the components.
The only other component to worry about is the capacitor. But really, the thing has to be the size of a roll of coins in order to worry about. Also, the electrolyte inside them is going to be nasty, but nothing else should be a concern.
Given that he’s 3, I’d stick with battery-powered devices. High voltage capacitors are indeed the most dangerous component of line-powered electronics, and although they can be treated safely, 3 does seem too young to handle all the necessary precautions reliably.
Battery-powered devices are pretty much free from these issues. A camera flash is one exception, but really the caps are too small to be a real danger. Still, it’s not a bad idea to exclude these things until the kid is older.
The telephones, walkie-talkie, and tape recorder are basically totally benign. You don’t want the kid licking the circuit boards, but basic handling is fine. If any have LCD displays, watch out for the glass–it is thin and can fracture easily if you try to pry it out the wrong way (that said, it will tend to stay in one piece, so this isn’t a plate-glass-window situation).
If you like, disassemble the stuff on your own and post the images here. We can identify any components you have lingering concerns about.
He’s barely able to control movements with coordination and have a conversation…right?
There really IS a danger of him eating small parts regardless of what they’re made of!
I will suggest lots of the most basic wood block sets so he has enough material to build something big. Maybe Lincoln Logs. Maybe a variety of smaller stuffed animals or action figures to be characters in his buildings. Definitely you do any disassembly projects … a 3 year old physically just can’t yet. I used to stand on the bumper of my Dad’s truck and point to engine parts and he would name them for me but no touching - too dirty. Don’t buy the cool Lego sets yet, he can eat them and you’ll do all the work. I think you’re still 2-3 years away from having a junior mad scientist but disassembling stuff with him could be a great parent/child activity.
Don’t EAT any of it.
Don’t CHEW any of it.
Don’t INHALE any of it.
Don’t break the glass.
These are good rules that children should learn, and this is a good teaching opourtunity.
All dust is dangerous. Some dust is more dangerous, but all dust is dangerous. Do not inhale dust.
Colors always used to come from heavy metals. Heavy metals are all dangerous. Lead oxides also taste slightly sweet, and lead poisoning from chewing on insulated wire is a known hazard for electricians. Do not chew on electronics.
Small objects are hazards if swalowed. Batteries and Magnetics are potentially deadly. Do not chew, suck, or hold in your mouth, items that you dissasemble.
Broken glass is sharp and dangerous. Glass envelopes may safely contain material that is poisoness when released. Vacuam tubes, particularly CRT tubes, may decompose explosively when cracked.
Apart from the CRT tube, I’d be worried about him/her cutting himself, and I’d supervise if he’s not wise enought to avoid chewing/sucking/holding
I notice everyone posting here is still alive, rather than the ones who got blown up or electrocuted as small children…I survived sticking a screwdriver into an electrical outlet when I was eight, but I don’t recommend it as a part of growing up.
My daughter is now eight, and I would say she seems about average physically compared to her peers. Her fine motor control is such that, if she were interested in assembling and disassembling electronics, I would not in a million years let her do it unsupervised. I don’t think a three year old could do this effectively without major intervention by a parent. Never mind capacitors blowing up–what about a serious burn from a soldering iron?
I did make my own circuits as a kid, and after I’d been taught how, I did it without supervision. I started around 10. I’m not sure I’d be that confident in my daughter, but I would have to see how she did under supervision first.
Learn how to find and download repair manuals from the Internet. At the front of each manual should be a series of cautions and warnings about potential hazards. Discharging capacitors from televisions and microwaves is a one time thing. As long as they don’t get plugged back in again, there’s no chance of further harm. Just make sure you follow the appropriate repair steps from the manual before you hand it to your kid and it will be fine.
Have the freon professional removed from A/C’s and refrigerators, discharge any big capacitors and cut off any plugs that can be used to re-energize the circuitry. Older electronics may have PCBs in a variety of places; asbestos, arsenic, mercury can be found as well.
I honestly think there’s too much mischief you and your child can get into here, maybe start with a car engine tear down first.
The dangers of dismantling modern electronics are very over-rated. Gone are the days of huge, high-voltage capacitors. When I was a budding Electronics geek, I used to take apart junk that I had found at hamfests, and in those days high-voltage was common, and big, HV capacitors were everywhere. These days, everything runs on 3.3v, so the only place you will find HV is in the power supply, and even there the capacitors are much smaller than in the old days of linear power supplies.
There is still some finite danger in old CRT TVs, but it’s low, as long as the set has been off for a while (all modern CRT HV circuits have a bleeder resistor). Same for microwaves. Even so, I would reserve these devices for a kid who can follow basic safety instructions.
I remember playing with the flyback circuit of a TV I had salvaged, with the parts spread across my bed, making a Jacob’s ladder with the 15KV…
The issue isn’t the kid, the issue is the parent (or other adult supervisor). That person has to know what’s what. It’s not so much what the kid might do, but whether the adult really knows what’s good and bad about the possible dangers of any given device.
I remember taking apart my brother’s race cars trying to figure out how the electric motors worked. If you want to show your kids how electromagnetism works that’s pretty interesting and relatively safe.