Variac 20 amp advice?

[wadmancpu]

I've been looking online for a 20amp variac and I see Amazon has them for about $100 and Ebay has them for about $70. They all look the same but I'm wondering if there is any real difference between them? They all list brand names that are odd like vevor and others. Any advice would be appreciated. Thanks.

[sam_sam_sam]

Re: Variac 20 amp advice?

No there is no real difference in the ones that have a red outer case
The voltage meters are crap but you can do a modification to it and have a very good setup the meter that fit it also needs a modification for it be very useful

If you buy one and you want to do a modification to meter just let me know and will find the post where I did the modification to it and what type of meter that will fit

When I have some money to spend I going to this same setup on a 5 amp version of to be able to power LED strips to figure out what voltage the strips are ( wish list )

[wadmancpu]

Re: Variac 20 amp advice?

Thanks. If you could find the post on that mod that would be great!

[sam_sam_sam]

Re: Variac 20 amp advice?

Thanks. If you could find the post on that mod that would be great!

Here is the post where I talk about how I figured out how and where you have to the modifications

https://www.badcaps.net/forum/showth...to+transformer

Here is where you can get this meter at

https://www.ebay.com/itm/Digital-AC1...gAAOxygo9Q5Xoj

If you decide to get this meter and have in front of you I show you which diode that you have to remove and add a 1N4007 diode and add a piece of wire and some hot glue to hold it in place

[wadmancpu]

Re: Variac 20 amp advice?

Thanks!

[sam_sam_sam]

Re: Variac 20 amp advice?

I just bought the 5 amp version of it now because it getting harder to find this version when I look 6 months ago I found more Seller selling them now I see only handful of them selling them

So I will wait until until you have all the parts and we can do it at same time

[sam_sam_sam]

Re: Variac 20 amp advice?

Thanks!

How are coming along with getting the parts to do modification to the voltage meter

[japlytic]

Re: Variac 20 amp advice?

I fitted mine with a self-powered digital AC voltmeter which starts to display at 60V and above - any AC product would typically not work at such a low voltage.

[sam_sam_sam]

Re: Variac 20 amp advice?

When you do the modification that I am talking about you can read the voltage down 1.0 volts

The reason they can not read voltage down that low has do with the voltage divider to read voltage
You also have voltage reducer for the meter controller


In order for you to read voltage down that low you need to separate the meter power supply from the meter reading voltage divider circuit when you do this then the meter can read voltages that low

The meter that I have a link to can easily done you just have to —>

( remove one diode )
or
( cut the trace where this diode connects to the voltage input terminal block *** you have remove the top board of the meter controller in order to cut the trace you can also recap the board while you have it separated ***)

—> reroute the meter voltage divider circuit and hook it up to the outlet on the Variac

The meter power supply is hook to ON / OFF switch which now the meter is not powered by output of the Variac supply

One note

You do need to have a meter that can read its own power supply in order for this to work

Line / Netural you breaking the line side of the meter power supply / meter voltage divider circuit

[sam_sam_sam]

Re: Variac 20 amp advice?

Here is where I got the meter for the 5 amp version that I bought the one that I used in the 20 amp version would not fit in the same space

POWER GRID volt & amp monitoring GAUGE - Digital ampmeter / voltmeter combo 2in1
https://www.ebay.com/itm/POWER-GRID-...53.m2749.l2649

I will in next few days I show how I modified this meter module this was so easy to do
The modification to this board —> it shows where the 5 volt section for powering the meter so it can read down to ( [0] volts )

The modification is not finished and that is why I not showing it yet

[stj]

Re: Variac 20 amp advice?

$17 is fucking robbery.
i get them here:
https://www.aliexpress.com/item/32905549312.html

[sam_sam_sam]

Re: Variac 20 amp advice?

$17 is fucking robbery.
i get them here:
https://www.aliexpress.com/item/32905549312.html

I did not want to wait a month to get it

I want to have this device working for a project that I want start working on

I am going to buy some of these meters that you gave me the link to next month

I have four orders from AliExpress that I am waiting for over three weeks for and still have not gotten here yet

[redwire]

Re: Variac 20 amp advice?

For my variac project, I took apart that mini voltmeter and brought out the Vsense wire, so it's three wires now. It's powered off the input mains but measures the variac output, so I can dial down to a few volts AC. No <60VAC dropout of the voltmeter.

[sam_sam_sam]

Re: Variac 20 amp advice?

Here is the modification on this meter module that I was talking about

In the photo I show where I cut the trace so it can measure down to ( 0 ) volts

I replaced the only capacitor that is in this unit

It had a 330uf@16 volt capacitor but the same valve capacitor was to fat to fit in there that I had on hand so I use a 220uf@16 volt capacitor instead and seems to work okay with it

[sam_sam_sam]

Re: Variac 20 amp advice?

One note about this modification is that you have to cut the trace on both sides of board in the same position which I forgot to mention

[stj]

Re: Variac 20 amp advice?

you should create a bigger gap too.
specially people in europe with 230v - maybe even cut a slot in the pcb.

[sam_sam_sam]

Re: Variac 20 amp advice?

You are probably right about this however there is not really a lot of trace to work with if you are putting wires to the board

I did cut a deep slot in board on both sides

[sam_sam_sam]

Re: Variac 20 amp advice?

Here is a picture of the meter installed I just have to cut one corner off of the metal plate so the bolt at the top will work to put back on the cover

[sam_sam_sam]

Re: Variac 20 amp advice?

Here is the finished project here are some pictures of it

[sam_sam_sam]

Re: Variac 20 amp advice?

Here is the finished project here are some pictures of it

I used this for the first time on an old style rectifier module which I found out was working correctly