Very nice demonstration of this brilliant mod. I am just figuring out the way to do the same on the pzem-020 which uses a SMPS.

@The4Crawler

4 жыл бұрын

I don't have any details on that meter, but the concept is the same. Find the connection that feeds the incoming line voltage to the SMPS and then lift that connection and supply it from a separate source. There's likely some input filtering or a bridge rectifier in front of the small transformer. Should be able to use a continuity meter to find the line and neutral connections there from the input terminals.

@real-fakeuser

4 жыл бұрын

@@The4Crawler Just found a video about how to do it. In general the only thing needed was separate the two connected terminals by cutting out the traces inbetween ob both layers. Very nice module.

@The4Crawler

4 жыл бұрын

@@real-fakeuser Goods like a simple modification as well. I guess if I ever get one of that model, I may do the same thing.

@abizarlakdawalla4519

Жыл бұрын

@Real-Fakeuser I did get the pzem 020 and this mod would work though I ended up using an external DC source. I posted the circuit for the integrated power supply in the PZEM 020 and the way to modify it to read 0 VAC on my channel in case folks want to try it.

Is there a zero volt mod for the PZEM 61 like in the PZEM 21 where you lift one leg of the big capacitor for use in a variac?

This is a great video. I would like to put a ESP01 inside to the Pzem. Yes, to install in the same original PZEM box and connect the ESP in the TTL using 3.3/5v, and gnd from pzem. Is it possible? How?

@The4Crawler

Жыл бұрын

I've not worked with the TTL output model meter myself, so can't give any advice on that process. Try searching for wiring diagrams/schematics for the particular model meter you have. I have a link to a partial diagram on -061 meter in the vide description. Here's a writeup on connecting to the 004t meter: innovatorsguru.com/wp-content/uploads/2019/06/PZEM-004T-V3.0-Datasheet-User-Manual.pdf

A great job! As usual for changing something on an electronic board requires some knowledges in electronics. For avoiding short circuit what can we changing? I mean can I change a power supply for this wattmerer and give for example DC12V for avoiding short circuit between L and N. Because I want to use your method for our lab equipment and students can make mistakes during the lesson. Thank you, I hope you will reply for my question.

@The4Crawler

4 жыл бұрын

I think folks have done that. See the schematic: drive.google.com/open?id=1w80QYWeo8H5LdRoheGxNCMZViL9uqo81 and you'll see where you can disconnect the large capacitor and/or series resistor and tap into the V+ DC circuit, not sure what the zener diode voltage rating is but match that with your DC power supply.

@ruslan.zhumabai

4 жыл бұрын

Thank you!

Any chance of adding a schematic of the mods and the added resistor value? I see in the referenced videos they didnt add an additional resistor which is curious also. Thanks!

@The4Crawler

5 жыл бұрын

Sure, see link below, will also put the link in the video description: drive.google.com/open?id=1w80QYWeo8H5LdRoheGxNCMZViL9uqo81

@alrui

5 жыл бұрын

Hello & THANK YOU very much for the help, I appreciate it!@@The4Crawler

Intresting mod. When I connect my PZEM-021 up, I noticed the large resistor was getting hot, just wondering if this mod has something to do with this problem or is my one busy giving up. I also noticed you marked LIVE and NEU on your input, does it matter if I was to swop the LIVE and NEU. I see towards the end of your video you mention it does not matter, only if you modify the unit does it matter, am I correct , Thank You

@The4Crawler

Жыл бұрын

Yes and no would be the answer. That large resistor is part of the power supply, it's there to dissipate some of the power, as heat, resulting from dropping the high AC voltage to lower DC voltage for the circuitry. So, for example, if you're running the unit off 240V it'll get hotter than off of 120V. So, if you can feed the unit a lower AC voltage for power, it'll lower that resistor temperature. There's another mod out there where you bypass that whole part of the circuit and instead feed in a lower DC voltage, you can probably find that mod with a web search.

@vincentsale551

Жыл бұрын

Thank you for the info.

Any idea which cap you wire to on the PZEM-022? I tried with this guy's fix (community.openenergymonitor.org/uploads/default/original/2X/2/294bdb3c1419d8e6697bbeffa24d4ac3ee54ceb1.jpeg) but now my voltage is reading double... even without the 12VDC so I think I blew something in the circuit.

@The4Crawler

3 жыл бұрын

I haven't had a chance to try that new meter out yet. Maybe someone that has can chime in. With the 021 meter, I just figured out which of the 2 voltage sense wires was the hot side (that ran to the capacitor) and then I just lifted that capacitor leg off the circuit board and connected up a separate power wire to it. It looks like your post might be doing a low voltage power input. I can't see the image on that link and I've not tried a low voltage power feed. My fix just gives a separate AC input to power the meter from a fixed 120V source and thus allows the voltage sensing part to read down to 0 volts.

I'm wondering.... what is the purpose of the bleed resistor?

@The4Crawler

5 жыл бұрын

It's there to bleed off the charge in the input capacitor to minimize shock potential. On a 120V AC waveform, you can have a peak of 170V DC on that cap when the power is cut off. It will diminish over time on it's own, but a dedicated resistor can discharge the cap in a predictable amount of time. Required, maybe not. A lot depends on where the meter is installed and if the input circuit is likely to be accessible.

@mattrivers77

5 жыл бұрын

@@The4Crawler thanks!

Hi Sir, I also bought the meter and this hack works fine until 190V, then it trips and goes off. Strange

@The4Crawler

4 жыл бұрын

Assume you mean it works fine from ~240 volts down to 190 volts? I've not see that on mine, although I've only tested from about 170 volts down to 0 and that works fine. Normally, as shipped, the meter seems to run down to the 60-80 volt range. Did yours do this before?

@Tsjoetenbille

4 жыл бұрын

@@The4Crawler i live in europe. Mains is 230V. When in normal use, the meter starts up at +/- 30V. Goes to 270V (max variac). With this modification it starts up directly (light on, 0V) and goes up till 190V. Then light flashes and meter shuts down like it is going in protection.

@The4Crawler

4 жыл бұрын

@@Tsjoetenbille OK, that's clearer. With my setup (variac on 120V) I can only get up to 165-170V and the meter works fine. I have run one without the modification on 240V and that worked, but that was a fixed voltage. Maybe there is some sort of internal protection feature that kicks in higher the voltage I can get on my power supply. I'll have to see if I can rig up a 120-240 volt converter to test mine above 170V.

Is there a reason that you replaced your PZEM-061 meter in your variac with the 021? I've got an 061 and I'm ready to modify it so that I can measure the voltage and current output from my variac. If you think the 021 is a better meter, I'll pick up one of those for use on the variac. thanks

@The4Crawler

7 жыл бұрын

Mainly to read lower current levels a bit better. 0-20A vs.0-100A range and also figuring the shunt resistor might be more accurate at lower values than a CT: kzread.info/dash/bejne/Zmuj1ailYK_bepM.html I also had a plan for a meter with a CT so instead of buying another one of those, I picked up the 021 to swap into my variac. The meters seem to run down to about 60V: kzread.info/dash/bejne/m5dozbmdirDKlqg.html

@davidbrown3184

7 жыл бұрын

That makes sense. Thanks for the reference back to previous videos. I'm thinking out loud to confirm your meter mods, so please bear with me ;-) To hack your meter, you lifted the hot connection to the 1uf cap. You connected a new, external hot wire to the lifted leg to power the meter. You added a 470k bleed resistor in parallel with the 1uf cap. Is the neutral connection to the meter from your variac IN or variac out neutral or does it even matter?

@The4Crawler

7 жыл бұрын

Yes, you lift the leg of the 1uF cap from the input terminal block and feed that separately. The neutral connection is whatever the neutral of the measured voltage is: kzread.info/dash/bejne/rKR2uq2nc9bSnLQ.html So the separate power feed has to be referenced to that same neutral. Before you lift the leg of that capacitor, there is no real line and neutral connection (meter would work the same no matter how it's connected), but once you do there is.

Working on a similar project with 2 KW Isolation transformer and 1.5KW variac. Gonna be a very cool hack.

@The4Crawler

7 жыл бұрын

Wow, that sounds like a nice, high power supply.

@nomadic_rider42

7 жыл бұрын

R Brown when I saw the Ebay auction of the Isolation Transformer it did not seem to be big, when I received it, damn heavy. It weighs almost 15kg (33 lbs).) cannot find a proper enclosure.

@The4Crawler

7 жыл бұрын

Yes, a good isolation transformer is a beast. I was surprised how heavy the 0.7KW unit I have is, it's a big brick of iron and copper.

@nomadic_rider42

7 жыл бұрын

Luckily I've got a toroidal one, EI types are slightly heavier and bulky.

Thank-you for posting this. Your video and explanation are wonderful. I have a question about the 470K bleeder resistor. What wattage does it need to be rated for? Would a 1/8W or 1/4 W resistor be adequate? I will be making the same mod to an inexpensive VARIAC that I picked up on Amazon (see kzread.info/dash/bejne/qYR6w6d_dcjTksY.html). Thank-you

@TR3A

3 жыл бұрын

Never mind. I was able to answer my own question. For the US and Canada, line voltage is 120VAC RMS so that the capacitor max voltage would be about 170VAC. Using the formula P=(V*V)/R, we see that a 470K resistor will dissipate about .07W. A 1/8W resistor would be sufficient for any resistor >260K; a 1/4W resistor would be OK if 130K or higher.

@The4Crawler

3 жыл бұрын

Power = V*V/R, so not much power dissipation, about 1/8 watt at 240V. Bigger concern might be the voltage rating, could put 2 resistors in series if that's an issue.

Here's a link to another interesting mod of the PZEM meters. It looks like this user moved R3 on the rear of the circuit board and severed a trace on the front of the circuit board to effect the same change as your mod. If I were good at SMD soldering, I might attempt this version. Or I might just buy another $10 meter and have a go at it. ;-) alcodistillers.ru/forum/viewtopic.php?id=169&p=16

@The4Crawler

7 жыл бұрын

Looks like some interesting hacks on that page. Also has a variation to bypass the capacitive dropper and feed 12V directly to the voltage regulators.