Building a Touch Sensor Without Microcontroller

Рет қаралды 4,860

Күн бұрын

Here's my solution to making a touch sensor for my lamp that just uses a dual OpAmp and a D-FlipFlop.
I used an LM358 and a CD4013
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I forgot to mention it, but the wire that I connected to the tape and was touching can be connected to any metal frame that isn't grounded. This can increase the capacitance, making the RC low-pass filter necessary as I explain at the end of the video.
0:00 Intro and previous project
0:41 Initial idea overall explanation
1:28 Proposing improvements
2:02 PCBWay
2:41 Building step by step
4:27 Tips for building it
Music:
Kevin MacLeod - George Street Shuffle
Kevin MacLeod - Groove Grove
Kevin MacLeod - Lobby time
Kevin MacLeod - Space Jazz

Пікірлер: 26

@10e999 22 күн бұрын

Such a cool channel ! You have a new subscriber !

@bob_mosavo 25 күн бұрын

Thanks 👍

@Sctronic209 25 күн бұрын

Very nice.

@f33net 24 күн бұрын

Usually, there is a strong enough 50/60 Hz potential on the human body to simply detect it. And this will require 4 transistors, not 4 chips. 😉

@BillAnt 24 күн бұрын

Some people can actually feel the 50/60Hz when holding the metal body of a phone or other devices plugged into a charger. Myself included, it's a weird feeling sort of like a very low constant electrocution.

@f33net 24 күн бұрын

@@BillAnt That's not what you're talking about. And you will not feel 50/60 Hz from chargers, there are none there, the conversion frequency is much higher. :)

@BillAnt 23 күн бұрын

@@f33net - Whatever it is, I can feel it on some devices. It may be the buck-converter's frequency, but there's definitely something there.

@robstamm60 20 күн бұрын

@@f33netYou can actually get capacitive coupling of mains voltage into the shielding of isolated chargers - sometimes the voltage differential can even be high enough to be painful when touching the shielding.

@concretesloth2968 20 күн бұрын

@@BillAnt is it like a tingling/vibrating sensation when u rub a metal surface connected to a plug?

@Torogol85 21 күн бұрын

The LM358 is a general purpose op-amp, not a voltage comparator. This whole circuit works gracefully because the 358 is capable of impersonating a voltage comparator, and save the day unscathed. This is a nice, simple circuit which I would like to build, but I think I'll replace the LM358 with an actual comparator, like the LM393 (dual comp). Its open collector outputs require using a pull-up resistor

@5VLogic 21 күн бұрын

Good observations 👍

@__MINT_ 25 күн бұрын

Was the problem with triggering the circuit by interference solved? I've made a very similar thing a few years ago, and had the exact same problem. Now I think that I'd add a one way low pass filter (slow charge, fast discharge via a diode) at the comparator's input, so that very short pulse wouldn't be enough to create a clock pulse. Touching it creates very long pulse compared to the one created by interference

@5VLogic 25 күн бұрын

I think so but can't be sure because I haven't tested It thoroughly. The low pass filter is definitely a good idea, I should try that.

@tonys9860 24 күн бұрын

Have you tried touching the gate of the MOSFET to turn the light on and off? Without the other circuitry?

@BillAnt 24 күн бұрын

The MOSFET may be sensitive, but you need to hold a constant logic level, otherwise it would flicker, or worse burn out.

@Rouverius 23 күн бұрын

Cool. Wonder how the other flipflop could be used. Maybe to have two different light levels settings?

@88farrel 23 күн бұрын

I like your funny word magic man

@ahmedalshalchi 21 күн бұрын

Nice design idea but it is not commercially acceptable ... I recommend you use HT7704 series which will finish all without headache ..

@shawon265 22 күн бұрын

Isn't it possible to swap the flip-flop with another op-amp? Maybe a positive feedback circuit or something? It'd be hall cool if it can be done just on 1 quad op-amp ic

@5VLogic 22 күн бұрын

Yeah, that's a good point, I thought about it, because it would have been cool, but I couldn't think of an actual way to pull it off.