This reminds me the old days, when there was no or little coding in electronics. Everything was pure practical. The transistor based servo circuits, logic circuits, only a few ics were used. Today those forgotten circuits seem to be an alien tech for our new engineers, who have never gone through these.

@cucumber1389

2 жыл бұрын

I'm pretty bad at electronics but this is exactly the reason I refuse to get into coding. It's just so much more fun to actually build the circuit

@sgrimm7346

2 жыл бұрын

@@cucumber1389 " My preferred method of programming is a soldering iron"....Steve Ciarcia (Byte magazine). As is mine. I can code, 'basically', and I've held off getting into the arduino gold rush of things, but for practical purposes, have had to dive into it. However, nothing beats putting together a nice component level circuit and watching it come alive. This channel should be a pre-requisite for anyone wanting to learn real electronics.

@keithking1985

2 жыл бұрын

@@cucumber1389 Agreed 1000%

@cucumber1389

2 жыл бұрын

@@sgrimm7346 its of course fine to learn and use coding in projects if that suits the person, but to my preference I learn more doing physical electronics

@iMiilk182

2 жыл бұрын

@@cucumber1389 where is the fpga gang at? Coding the physical component

Cool video ! All you need now is a NC switch on the feedback line and you have a push on push off switch . These are great to drive a relay that controls mains power and an added bonus is they are also a no voltage reset switch like what you want on a lathe or milling machine , if the power goes out while you are operating it you don’t want it to start up automatically when the power comes back on .

@learnelectronics

2 жыл бұрын

Great idea!

@tinkering.online2007

2 жыл бұрын

The NC switch in the feedback line is a wonderful idea, too 👌🏼

Cool. Keep the classic circuits coming. Thanks. ☮✌

@learnelectronics

2 жыл бұрын

More to come!

I have forgotten SO MUCH electronics theory over the years. It’s fun to breadboard along with you and get some of it back.

@TheUnofficialMaker

7 ай бұрын

Use it or lose it!

This is precisely what I needed. Thank you for taking time out of your day to make this.

Wonderful explanation.Yes, people need to know these circuits!

These are my favorite short circuit videos.

@incxxxx

8 ай бұрын

First try to build and check if it is works. In my opinion it doesnt work as promised.

@Sh4dowHunter42

8 ай бұрын

Oh? I'll try it then.

@HansKliever

19 күн бұрын

nice one: "short circuit" videos... 😅

these latch circuits are Very handy to know and have in your arsenal to pull out when needed. THANK YOU PAUL. P.S. add a couple of cap's and another transistor and you can make it come on & off with the push of that button. which is another handy circuit, i hope Paul will show us that one too.

@incxxxx

8 ай бұрын

It does not work!

Pretty cool. Latches get confusing for me once you start getting into flip flops. I wish there was an easy way to remember the truth tables for every gate.

Excelent classic circuit, great video.

Nice lesson Paul, thanks.

😀nice, now the two transistor latch with set and reset inputs, Q and bar Q outputs plus a buffer, if it pleases you

Neato! Always impressed by simplistic ingenuity.

I just love these lessons. "Circuits you should know"😊

Very well explained and thanks for sharing from Belgium.

I juz realised, u don't need two 4.7K ohms resistor, u can juz share the resistor. Loved the classic circuits, Paul. Keep it coming!

@Enigma758

2 жыл бұрын

Exactly!

Man you are life saver I search the whole internet for something like this but allI see is rubbish thanks alot 🎉

This is the best videos. I really like them. Thanks

Notified 3days late. Get it together 25Tube. Great choice on thee most basic circuit anyone should know series. God Bless

Awesome just what I was looking for ..

More classic circuits!

Awesome ! ! That's just what I needed.

Perfect Video mate! You're a gentleman and a scholar.

Thanks for sharing this! I've been learning quite a bit from your channel. One thing that helps me is when you lead with an example of why a design is used or is important before going through the design. It sort of sets the stage for me as you go through it. Just my personal preference though. Best wishe! - Tom Z

Thank you. Nice simple circuit.

@incxxxx

8 ай бұрын

Nice simple but it does not work.

nice circuit good explaination nothing to say but thank u

@incxxxx

8 ай бұрын

First try to build and check if it is works. In my opinion it doesnt work as promised.

Good video. A useful circuit when a scr is not around.

Cool circuit.

Very interesting circuit to be applied to model railroading electronics. Thank you! Maybe can you reset the circuit by connecting a push button between the base of NPN and gnd?

@oldwrench4213

2 жыл бұрын

Yep. Just use another switch.

@Enigma758

2 жыл бұрын

Yes, and the advantage is that you can use a common normally open switch (as opposed to a normally closed switch on the feedback connection).

add a nc button to the base of q2 for a reset

Good way to tell if mains circuit went off while you were gone. Lets see some SCR circuits.

Clear af. Thanks.

@incxxxx

8 ай бұрын

First try to build and check if it is works. In my opinion it doesnt work as promised.

it was a helpful video.

@peterdavidson3242

2 жыл бұрын

Wrong place

Thanks Dear❤

I don't know if anyone ill care to answer this but I'm an educator who needed the circuit for a project and I do not understand the reason for many of the resistors. I get the 1k completely as the current will follow the preferential path once Q1 is open. I breadboarded this on a 3v system. But the reason for the 10k and 4.7k elude me. I know the circuit does not work without them but I do not understand why. I am guessing that the current to the bases needs to almost be miniscule compared to the current flowing through the transistor or adverse effects will happen. Thanks to anyone who takes any time to provide a run down.

Изобрёл тиристор, только зачем-то еще 4 лишних резистора добавил.

I knew that in the 70's good to see again thanks, you need a bigger LED :). How about adding a time delay to let it go off

The PNP transistor gets turned on when it has a path to ground through the NPN transistor. Is that a correct statement? Kinda new here

Thank you for this practical circuit idea ⚡︎ 🔋 🧰

@incxxxx

8 ай бұрын

First try to build and check if it is works. In my opinion it doesnt work as promised.

I ike it, fascinates me how PNP transistors turn on. Tip on how to remember the arrow: NPN: Not Pointing iN

How do I stop? Thank you very much

I really enjoy your videos. I learn so much from them. Some feedback from a beginner... I see a lot of videos where resistors are put into the circuit, but very little explanation is given as to why, or why the value chosen was chosen. I know in this video, you mentioned using the first 4.7k resistor so you weren't "jamming the transistor open too hard"... but I don't really know what your definition of jamming is in this case. Everyone seems to ALWAYS remind us EVERYTIME why they put a resistor with an LED, but very few discuss it on non-LED components, and it's frustrating. For example, if I want to recreate this circuit, but don't have a 5 volt source, how would I know how 9 volts (for example) affects the 4.7k resistor if it's purpose and value isn't explained? Thanks again for the videos... I could have JUST used this technique in a circuit I made. Very helpful.

@commenter4799

9 ай бұрын

It's worth delving into deeper with a dedicated resource to learn the details because it's a deep topic. A transistor is a current amplifier, so for an NPN knowing there will be about a 0.7 V drop from the collector to the emitter and a 0.2 V drop from the base to the collector assuming saturation mode, you can determine the current going into the base. Then, you can look up the datasheet and see the rated gain which is usually at least 300. So, without the resistors, a small current to the base could result in a large current (300 times larger) from collector to emitter, and could easily destroy the equipment. A transistor is similar to two diodes back to back, so just like an LED can burn out from too much current, so can a transistor. Not that I would ever burn up a bunch of transistors trying to make an H-bridge. The resistors help save power also, as often a large current isn't needed for digital logic. To determine the correct values if you were using a 9V battery, you can use mesh analysis which is it's own topic and far harder with transistors, at least for me.

Made by mr class himself. Mr Paul. Ty buddy. Always a pleasure. Ty for the Ukraine fund raiser, I have tons of relatives their. One of my uncles had a farm near the Belarusian boarder and was hit in the first day. Their all ok. Most have retreated to the western boarder allies. The ones who stayed to fight are good and optimistic about winning. The soldiers that they fought so far are young and misinformed.

@learnelectronics

2 жыл бұрын

Im praying for everyone involved.

@melplishka5978

2 жыл бұрын

@@learnelectronics ty bud

Hey! I have been strugglimg to build this for almost a month now, i calculate the necessary resistances for my transistors, the transistors work separately but i can never quite make it work. what do you think could be the problem? the NPN transistor always conducts for some reason. do you think the collector emitter current exceeds a limit?

@incxxxx

8 ай бұрын

Yes indeed, it doesnt work.

Hello, amazing video, can anyone explain to me if it's possible to make a similar circuit using 2 npn transistors? If not, why?

@incxxxx

8 ай бұрын

First try to build and check if it is works. In my opinion it doesnt work as promised.

Honest question, why not just use both transisters as an scr instead of all the resisters and everything? Learned alot from you though, thank you for l what you do!!! ❤

@learnelectronics

2 ай бұрын

It's just one way to do something. This is a common circuit that you will see in use.

@arcadebuilder533

2 ай бұрын

@@learnelectronics gotcha, thank you 🙂

Hey Paul, I built this circuit and when I connect to power the latch is energized before I press the button. If I ground the emitter on the Q2 then it de-energizes and the button energizes the latch as intended. Any idea how I can make it stay de-energized when I connect the circuit to power?

@eliasmiranda3503

Жыл бұрын

I have the same trouble, think that is for the leakage current param

I used different NPN and PNP transistors (just general purpose ones I had on hand) plus 10k resistors instead of the 4.7k ones (since thats what I had to hand) and found that just touching any of the wires/circuit latched the circuit (LED came on). I assume this is noise and parasitic's. The NPN transistor I used turned on at 560mv and it wasn't hard to create that level of noise just tapping the wires (or pressing on the underside of the breadboard!). In any case I put a 0.1uf cap from the NPN Base and ground and this seemed to solved the issue. Just starting to learn this stuff so not sure if this was inspired or just coincidence....

@jeffmeds

Жыл бұрын

yes i had the same problem thanks for the fix.

Cool..

With the inverter, the very building blocks of digital electronics

can this handle 12 volts?

Beautiful tutorial. Dog is more interested in classic "Tom and Jerry" bone, perhaps!

@incxxxx

8 ай бұрын

First try to build and check if it is works. In my opinion it doesnt work as promised.

👍

Would a push button between vcc and the base of q2 shut it off?

@learnelectronics

2 жыл бұрын

A NC across VCC would do it. Press the switch, interrupt the current and it will go off.

Why not use two NPN transistors? (Just learning) 😁👍🏼

By "N-channel" and "P-channel" I think you mean NPN and PNP. These are not FETs.

I tried to replicate your circuit but can’t get it to work correctly. When I turn on power, the LED comes on and stays on without triggering the button. However, if I unplug the 5v lead from the emitter of the PNP, and then reconnect back in place, the light stays off until I press the button, at which point the circuit works correctly and latches as it should. I used all the same components and values as you and even swapped out the transistors thinking they may have been faulty, but no luck in getting it to work correctly. Any ideas on what could be going wrong?

@incxxxx

8 ай бұрын

Your right.

What's the reverse of this? How do you turn off the led with the same switch?

@learnelectronics

2 жыл бұрын

You don't. That would be a toggle circuit. This is a latch.

Can we not make this circuit with only one transistor?

NPN..Needs Positive Nput...PNP...Put Negative Please...

@chrisingram7277

2 жыл бұрын

I like it, now to burn it to my permanent memory :)

Am lost 😢can u direct me to learn the basics

Still don't know why emitters are called emitters and collectors are called collectors when they interchange between pnp's and npn's.

First! Lol Great topic Paul!

@incxxxx

8 ай бұрын

First try to build and check if it is works. In my opinion it doesnt work as promised.

The problem with this one is that there is no reset.

Similar behavior as thyristor isn't it?

@learnelectronics

2 жыл бұрын

Closer to an SCR but yes

@worvtube

2 жыл бұрын

I thought they are the same device just called different in some countries. ..or am I wrong?

why not 557,547

... and no de-bounce logic required

It does not work according to your sketch. Too simple to work correctly. Values of resistors are not correct.

This is how the RAM stores data, part of the flip-flop. The sad thing is that nowadays in a digital electronics course usually they don't explain to you how the latch is made with relays or transistors, just the truth table. And I was wondering for a long about it. In the past in courses like this everything was explained from the very beginning.