I have a digital AC volt meter which can withstand 70v to 500v and it has two wires to the AC input. How can I turn on the led (volt meter)? Without using an AC input volt to turn it on. Is it possible to supply it with external DC power source and use the AC input to supply the meter with an AC volt.

My problem is I build AC volt supply which I use a potentiometer to adjust the voltage and the AC voltmeter is connected parallel to the AC output. The meter does not display or turn any volt when the volt is adjusted to 20 but turns on when the volt is at 80v

Please, if any of you have the circuit diagram kindly share it with me

 

I strongly recommend that you do not attempt to modify that meter. It uses a capacitive dropper transformerless power supply and it is not isolated from whatever the input is. It is dangerous to do anything to that circuit without very thorough knowledge of how it operates.

Even then, I can't tell from the photo is splitting the display supply is practical.

Just buy something else.

 

I strongly recommend that you do not attempt to modify that meter. It uses a capacitive dropper transformerless power supply and it is not isolated from whatever the input is. It is dangerous to do anything to that circuit without very thorough knowledge of how it operates.

Even then, I can't tell from the photo is splitting the display supply is practical.

Just buy something else.

Ok but do you have schematic diagram?

 

I agree with Yaakov. I don't understand why you would want to modify this meter. Isn't the purpose of the meter to monitor the AC voltage supplied?

 

M

I agree with Yaakov. I don't understand why you would want to modify this meter. Isn't the purpose of the meter to monitor the AC voltage supplied?

My problem is I build AC volt supply which I use a potentiometer to adjust the voltage and the AC voltmeter is connected parallel to the AC output. The meter does not display or turn any volt when the volt is adjusted to 20 but turns on when the volt is at 80v

 

The meter does not display or turn any volt when the volt is adjusted to 20 but turns on when the volt is at 80v

OK I understand what you trying to achieve but without a schematic I would not recommend trying to modify.

 

OK I understand what you trying to achieve but without a schematic I would not recommend trying to modify.

Even with a schematic, I would always counsel a person who doesn't already know how to reverse one from the board, etc., to leave it alone. It is a high potential, and it is mostly unprotected. It's just asking for trouble.

 

I would always counsel a person who doesn't already know how to reverse one from the board, etc.,

what do you mean by this- I don't wanna trace by wasting a lot of time, but I rather need a schematic?

 

What we're telling you is that a schematic isn't going to give you the secret to turning it into a DC meter. Since it doesn't operate below 80VAC then it's not going to work below that voltage.

The circuitry is poorly designed, and therefore represents a hazard to anyone who doesn't fully understand the circuitry. Not casting dispersions on you - but unless you're an electronics engineer you're probably not qualified to tinker with it. And if you ARE an engineer you wouldn't be asking this question.

One of our missions here on AAC is not to cause any harm to person or property. The small wires leading to that device suggests it draws very low current. There are no provisions for measuring any other voltages such as DC. The best recommendation anyone here with good sense would give you is not to mess with it. If you want a DC meter just buy one. They're dirt cheap and come directly to your door.

 

But unless you're an electronics engineer you're probably not qualified to tinker with it. And if you ARE an engineer, you wouldn't be asking this question.

I get it, but I want to tell you that not only do novices come here looking for help, even experts, come looking for help. For learning, even the sky also isn't the limit. There shouldn't be any limitations to learning. Learning increases one's cognitive ability and efficiency. Even if you know that you have to humble yourself to learn more from others "because there are many ways to hunt a cat" thank you.

 

Unless someone has already reverse-engineered that exact digital meter you are most unlikely to find a schematic. Manufacturers rarely publish such info.

 

I get it, but I want to tell you that not only do novices come here looking for help, even experts, come looking for help.

…

Even if you know that you have to humble yourself to learn more from others "because there are many ways to hunt a cat" thank you.

An expert would not ask this question. A neophyte should get the answer you were given: “this is a dangerous and unproductive thing to do“.

Hunting cats is also not a recommended activity.

 

Why are you using a meter rated for 70 to 500VAC to measure 20VAC? Just get the appropriate meter.

Bob

 

I get it, but I want to tell you that not only do novices come here looking for help, even experts, come looking for help. For learning, even the sky also isn't the limit. There shouldn't be any limitations to learning. Learning increases one's cognitive ability and efficiency. Even if you know that you have to humble yourself to learn more from others "because there are many ways to hunt a cat" thank you.

For sure I'm no expert. And yes, I've been here many times asking for help with a wide variety of projects. And most important is that I haven't attempted to do something that is beyond my capabilities. When others recommend caution - I listen. When others recommend foregoing a project - again, I listen. There's wisdom in the masses. There's also wisdom in knowing ones limitations. I'm limited. Sometimes severely. I wouldn't attempt to build a radio - it's way beyond my skills. Build a computer? I can't even begin to describe how inept I would be at that. But yes, I come here to learn things.

One must learn to crawl before they learn to walk. One must learn to walk before they learn to run. One must learn to run before they learn to fly. There's a progression to learning. When you were in fourth grade you didn't learn calculus because you didn't have the rudimentary basics down first. Same with algebra. You had to learn to add and subtract before you learned to multiply or divide. The progression is natural. We're suggesting you slow your roll. You wouldn't build an airplane out of stone, nor would you build a boat out of window screen. Wood is better for airplanes and boats. That is - there's a correct approach to everything. Using a high voltage AC meter to measure low voltage DC is like stone and screen. There are better ways to skin a cat.

None of us mean to make you feel small. We ALL were small at one time. But through natural progression we've learned to whatever level of electronics experience we each have. We can show you a better way to approach your project. Better yet, we can advise when something is the wrong approach. The approach you seek is better served getting the correct materials rather than attempting to make a silk purse out of a sow's ear. The greatest course of wisdom is to listen to those who know more and have more experience.

 

An expert would not ask this question. A neophyte should get the answer you were given: “this is a dangerous and unproductive thing to do“.

Hunting cats is also not a recommended activity.

Ok, sir, I get you any way I have already solved this problem 3 days ago, it is just that I delayed replying to messages because I was busy designing a blog website for myself. Thank you all.

 

For sure I'm no expert. And yes, I've been here many times asking for help with a wide variety of projects. And most important is that I haven't attempted to do something that is beyond my capabilities. When others recommend caution - I listen. When others recommend foregoing a project - again, I listen. There's wisdom in the masses. There's also wisdom in knowing ones limitations. I'm limited. Sometimes severely. I wouldn't attempt to build a radio - it's way beyond my skills. Build a computer? I can't even begin to describe how inept I would be at that. But yes, I come here to learn things.

One must learn to crawl before they learn to walk. One must learn to walk before they learn to run. One must learn to run before they learn to fly. There's a progression to learning. When you were in fourth grade you didn't learn calculus because you didn't have the rudimentary basics down first. Same with algebra. You had to learn to add and subtract before you learned to multiply or divide. The progression is natural. We're suggesting you slow your roll. You wouldn't build an airplane out of stone, nor would you build a boat out of window screen. Wood is better for airplanes and boats. That is - there's a correct approach to everything. Using a high voltage AC meter to measure low voltage DC is like stone and screen. There are better ways to skin a cat.

None of us mean to make you feel small. We ALL were small at one time. But through natural progression we've learned to whatever level of electronics experience we each have. We can show you a better way to approach your project. Better yet, we can advise when something is the wrong approach. The approach you seek is better served getting the correct materials rather than attempting to make a silk purse out of a sow's ear. The greatest course of wisdom is to listen to those who know more and have more experience.

Wow, I like this message and it is very informative. Anyway, I'm not ignoring anyone's advice

Thanks to everyone for your advice.