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So simple, why didn't I think of this. Thank you for sharing.

Nice little project. I've just 'discovered' you and am now a new subscriber

You could revisit the project and add a RPM counter. A small microcontroller would do the trick... ATtiny85, or Arduino.

Maybe follow up with a milliamp adapter circuit. I built one with a dual op amp, IIRC. It works extremely well.

Excellent project, circuit investigation, construction and video. Thank you for sharing.

The track cutting tool is called a "spot face cutter" for some reason! It's still available from the usual places. Although a small twist drill will work.

Joe I’m well up on stuff would you like to make a fox radio and how it works? Joint video long reason why , love ya videos keep going all the best from Hertfordshire

😊

Thank you. That was fun.

Hi, I could do a build video if I have requests for it. If not just a simple short video with the schematic . Which one do you want ?

When you say “ask for the schematic for the old style,” do you mean you’ll do a build video?

My TC1 Tester used to discharge in few days without use. I thought the battery was small. I replaced the cell with a larger capacity. But the problem didn't solved. After watching this video, I done the same. Now my cell continuously work without any problems. THANK YOU VERY MUCH SIR . ❤❤❤❤❤❤❤❤❤❤❤❤

Hi, I was really surprised by this .I have seen zinc carbon batteries fail many times. “ good makes “ included, athough less likely than alkaline.I think alkaline batteries actually produce hydrogen gas which causes the seals to leak.

Interesting, I wonder if that is true of all zinc carbon batteries? I've had numerous cases of alkaline batteries leaking after a few months or years, especially Duracell. Maybe we need to go back to thease for low power devices to avoid the dreaded leaking.

Just shows we gone backwards. Technological dark ages ahead. Keep staring at them screens kids nothing to see here

С такими питуханскими партаками

Will do that to mine immediately. Nice and simple. Switch ON for charging!

I'm going to pretty much just install any small toggle switch I have on hand; a simpler, cheaper, and faster modification. I've also not found any "micro" style push-on/off button switches that are electrically reliable for any reasonable amount of time before I'm replacing them.

7:35 did the max voltage trim affect the minimum?

i wonder, if you turn off battery is not reseting calibration settings?

Thanks for a very thorough review and test! I've been researching this very board and others have mentioned the 'fake' op amps and you've certainly proved that. I'll probably go for a lower voltage transformer as you suggest. Also I think a multiturn pot for the voltage would be good. I agree it's agood design, but not suitable for a 3 amp output just because that's the max rating of the input diodes!! Still it's a very cheap option even after getting proper op amps and transformer. Do you think it will function OK with a 12 volt transformer ? I may go for 15 volts anyway to give abit more flexibility to give maybe 18 volts DC out. I've subscribed to your channel, thanks.

I did the same, but used a small toggle switch so i can easily tell when it's off by looking at it. It's definitely worth doing..

Thanks for the video. I have several instruments that could use a mod like this. You might consider gluing a ring around the switch so it can't be activated when the instrument is bumped. I have that trouble with one instrument.

Hi, I like your modification procedure. Would you please tell me what the switch is called and where to find it? Having the same problem with my tester. Thank you.

Nice that you admit making a mistake. Good show.

For the lesser mortals, you didn't say that you must switch the unit ON when you need to charge it. 🙂

Great idea, mine is exactly the same, where did you get the switch?

I have the T7 version of this tester, they seem to have fixed the problem, I can leave it for months and it does not go flat in storage.

I got one of this kit and I built it. While I was using it with a 9V, 12V or 15V transformer, it worked very well. But when I powered from an 24V transformer (12V+12V) it suddenly died. I traced the fault to those opamps (TL081), two of them were faulty. Maybe theirs max voltage was lower than specified. However, I ordered 3 more and when I tested them, each behaved differently. I made an oscillator on a breadboard to test them, and all oscillated but the waveform was different for each one. I then bought 3 more, from a local shop and I got 3 ICs each one different but two of then behaved identical in the oscillator test circuit. So, I used those two and another one known good IC. I tested every component on the board and each one tested good. However, when I installed the ICs, the PSU did not worked, even with an 9V transformer. It went into current limit (the LED was on) and the output voltage stayed at 0.3V. I found that the negative voltage generated went to -0.6V when IC3 (the one that went in flames in your circuit) was connected and that IC was warm. With another IC, the V- was the intended -5V but the output voltage was 0V. Now I am planning to remake the kit with my own parts, each one selected and tested, just to see what is wrong with it. My guess is that these opamps are not originals, maybe clones, and theirs Vcc need to be lower than the original datasheet specify.

Hi Jonathan - man, I'm honoured! Love your mods - this is exactly why I started this youtube thing! Keep up the good work - talk to ya soon!

Hi. Extremely well done for your first video. Carlos from the electronics channel here. Will have to up my game now 😂😂😂