How to make a single transistor oscillator

hey what's happening guys happy Saturday to you the other day when I did the video on the tiki torch teardown somebody had commented and said that that's all people do anymore is program microcontrollers and I commented back and I said I agree with you there's just really no finesse in electronics anymore so I thought I would make this little video to show you something that I think is a little bit interesting has a little bit of finesse to it and challenge you guys to come up with something - if you take a look here what we got going on what do you see well you see an LED capacitor a resistor in a transistor and you might notice something a little interesting that base on the transistor is floating free it's not connected to anything and this is 2n 22 22 so it is emitter base collector starting from the left so what you see here is we're putting 12 volts in here VCC this is our load resistor coming down going into the emitter coming out the collector going to the LED going to ground and in parallel across the transistor is a hundred microfarad electrolytic capacitor what we have here might be kind of deceiving because this is actually a single transistor oscillator and it is actually oscillating right now if I take the probe here and will probe the output which is actually the collector in this case of the transistor hold on I got the light on okay what do we see there we see a sawtooth wave pattern at about 30 Hertz so that's weird right this transistor is operating in the reverse avalanche mode it's a reverse breakdown operation of the transistor and this will work with most NPN transistors but to things you might have to play around with are the voltage it definitely needs around 12 volts to overcome the breakdown voltage and even if you have a bunch of 22 22s you might have to try a bunch of different ones till you get it to work in my case I ended up having to go through three of them it was the third one that actually started the oscillation now the speed of the oscillation is controlled by the capacitor here now we looked at that and we saw about 30 Hertz which is why this appears to be solid so if we double up I don't have any 200 so we're just going to throw in another 100 micro farad capacitor in parallel with the first one remember capacitors in parallel doubles your capacitance I can get it let's go in come on there you go all right so now maybe you can see a little bit of oscillation there so let's get up here once again and we will too many wires floating around in here will probe the output and rotate up and what do we see well look at that now we're at about 15 Hertz so by increasing the capacitance we can increase or I'm sorry decrease the frequency see yeah you can definitely see the flicker there let me make a little bit darker I really didn't help did it alright let's try this I'm gonna pull out these two 100 nano ferret and here is a 2,200 let's see what this does I haven't tried this yet so hmm it is not going all the way off is it I can see it pulsing can you see it pulsing let's uh let's probe that output let's see what we get here interesting it is pulsing but wonder why that is you guys have any ideas let me know let's try uh I think I've got one other larger capacitor here yeah I've got a 3300 let's see if I can coax it into the OL breadboard and see what we can get in the holes you go come on they're going in there nope not particularly let's go back to our - 100 make sure you put those in the right way otherwise things could go bang we don't want that to happen again yeah okay hold on I got room maybe I can get one more in there all right I found another hundred let's see if I can find a spot to get her in there that should have cut us down to somewhere around seven unless you're getting [Music] well it says this below 10 let me roll up here yeah saying it's below 10 and hmm that's a major yeah one moment please so I added the frequency measurement down here nine point nine point nine I thought I'd been lower about seven but what I always tell you guys things are never exact when it comes to electronics you're always going to have loss parasitic capacitance and the like but you can definitely see it is oscillating there and I think that's pretty cool so I'm just going to yank out these extra guys for now and if we rotate back up you can see we are back well some reason seems to think we're over at kilohertz that's not correct okay there we go we're back to 30 Hertz so that's pretty cool I hope you guys enjoyed this if you did give me a thumbs up feel free to comment share and don't forget to subscribe big thanks to all the patrons that's it I'm out peace [Music] you

Channel: learnelectronics

Views: 67,352

Rating: 4.7341299 out of 5

Keywords: How to make a single transistor oscillator, led flasher, how to make, electronic oscillator, reverse breakdown

Id: I-YANhpiUCQ

Length: 8min 23sec (503 seconds)

Published: Sat Jun 23 2018