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Your cart is empty.Brock Wood
2025-09-04 13:29:02
These little voltmeters work just fine. The meter has three wires: red (positive) and black (negative) to power the meter, and a white wire you connect to the point where the voltage is being measured. There is a tiny Phillips screw on the back of the meter to calibrate the reading. I found that the little voltmeter agreed with my multimeter down to a hundreth of a volt. I did not need to calibrate the meter. These are inexpensive and work well. I like them.
Ken Simmons
2025-08-29 16:57:37
I purchased these units "on a whim" because they looked like interesting things for "experimenters".First off, they come with ZERO "DOCUMENTATION"! With that typed, here is what you need to know.1. They're good to 30 VDC MAXIMUM.2. They WILL NOT read "negative" input voltages!3. The RED wire is for DC supply voltage (3-30 VDC)4. The BLACK wire is the COMMON RETURN5. The WHITE wire is the MEASUREMENT wire (0-30 VDC input)Connect the RED AND WHITE wires to your "supply", and BLACK to "ground/return". If the voltage is GREATER than 3 VDC (30 VDC MAXIMUM!), the meter will "self-monitor" the DC voltage. If you connect the RED and BLACK wires to a separate source (i.e., 9V battery), use the WHITE wire as a "voltage probe" (0-30 VDC input, NO "negative" polarity!) and the BLACK wire as the "ground reference", like a DMM. You'll have 3-digit accuracy in your readings and the units will "auto-range", moving the decimal point appropriately.Finally, I strongly suggest you "calibrate" these units using a Precision Voltage Reference (i.e., KKMoon - see my review on it!). Power the module using a 9V battery (RED and BLACK wires), and connect the Voltage Reference between the WHITE and BLACK wires. Chances are you'll have to ADJUST the unit via the VERY SMALL potentiometer on the back (use a 2mm blade screwdriver) - BE PATIENT as a small "tweak" can "greatly" vary the display!Once you "calibrate" the units, they can easily be integrated into "low-voltage" circuits as monitors. BY THE WAY: the BLUE 7-segment displays are REALLY BRIGHT - you may want to get some blue-tinted plexiglas to make "display windows" for them. I hesitate to think how bright the other available colors are...
Erik
2025-08-17 15:51:42
They all seem a accurate, and only had to adjust one of them by 0.1V based on the reading from my Fluke meter. Bright display, easy to read. Like the Three wire set up for reading voltage of same device or separate one.Dislikes... With the lack of a bezel you need a CNC machine to cut out a accurate hole to mount them and still look nice... See picture.... The wires come out the top of the board... See other picture... So when you mount it thru the plate. You need a couple washers to space it so it rests flat. If the wires were soldered to the other side of the board, this would not be an issue.Still would recommend
Larry S
2025-08-16 11:47:01
These are great little devices. I build various size battery packs and use these to determine their state of charge. The wide voltage range of 0-30v is perfect for my application They are very easy to use. If you don't need to measure
Aubrey Sheldon
2025-08-06 18:43:50
These work great. I have a very accurate digital multimeter and used it to check all 5 (powered from the same 5 volt source). They did not all read the same, but there is an adjustment potentiometer on the back (you need a very small flat blade or Phillips screwdriver to adjust) that allows you to easily calibrate the meter. Once this is done (or confirmed), the device holds calibration well. I won't hesitate to buy more of these if/when needed.
Joel Aycock
2025-08-04 12:30:55
Very nice. I measured only 0.05v error uncorrected at 12v (there is a pot to correct in case of larger error, but no correction was necessary in this case).Bright with little current draw- I measured only 10ma draw from my 12v battery (I tied white & red leads together so that the meter was powered from the battery being measured).Cheap & accurate, and quick delivery. What more could one want?
One of the guys
2025-07-25 16:19:08
Work perfect and the cost is excellent.
Eduard
2025-07-24 16:14:16
Solo eh probado 1 pero funciona a la perfección
Edgar Trujillo
2025-07-11 11:18:19
Fácil de conectar y usar, no estaba bien calibrado, pero es sencillo de ajustar.
Kunde
2025-07-07 15:59:33
Los productos llegaron a tiempo y corresponden a la información, estoy muy satisfecho y lo recomiendo encarecidamente.
Donald Hebig
2025-06-21 16:58:20
I disliked the false advertising and different product was shipped than what is advertised. It is missing the voltage calibration screw on the back.
Brock Wood
2025-06-17 13:50:19
These little voltmeters work just fine. The meter has three wires: red (positive) and black (negative) to power the meter, and a white wire you connect to the point where the voltage is being measured. There is a tiny Phillips screw on the back of the meter to calibrate the reading. I found that the little voltmeter agreed with my multimeter down to a hundreth of a volt. I did not need to calibrate the meter. These are inexpensive and work well. I like them.
Ken Simmons
2025-05-31 18:57:15
I purchased these units "on a whim" because they looked like interesting things for "experimenters".First off, they come with ZERO "DOCUMENTATION"! With that typed, here is what you need to know.1. They're good to 30 VDC MAXIMUM.2. They WILL NOT read "negative" input voltages!3. The RED wire is for DC supply voltage (3-30 VDC)4. The BLACK wire is the COMMON RETURN5. The WHITE wire is the MEASUREMENT wire (0-30 VDC input)Connect the RED AND WHITE wires to your "supply", and BLACK to "ground/return". If the voltage is GREATER than 3 VDC (30 VDC MAXIMUM!), the meter will "self-monitor" the DC voltage. If you connect the RED and BLACK wires to a separate source (i.e., 9V battery), use the WHITE wire as a "voltage probe" (0-30 VDC input, NO "negative" polarity!) and the BLACK wire as the "ground reference", like a DMM. You'll have 3-digit accuracy in your readings and the units will "auto-range", moving the decimal point appropriately.Finally, I strongly suggest you "calibrate" these units using a Precision Voltage Reference (i.e., KKMoon - see my review on it!). Power the module using a 9V battery (RED and BLACK wires), and connect the Voltage Reference between the WHITE and BLACK wires. Chances are you'll have to ADJUST the unit via the VERY SMALL potentiometer on the back (use a 2mm blade screwdriver) - BE PATIENT as a small "tweak" can "greatly" vary the display!Once you "calibrate" the units, they can easily be integrated into "low-voltage" circuits as monitors. BY THE WAY: the BLUE 7-segment displays are REALLY BRIGHT - you may want to get some blue-tinted plexiglas to make "display windows" for them. I hesitate to think how bright the other available colors are...
Erik
2025-05-28 18:49:36
They all seem a accurate, and only had to adjust one of them by 0.1V based on the reading from my Fluke meter. Bright display, easy to read. Like the Three wire set up for reading voltage of same device or separate one.Dislikes... With the lack of a bezel you need a CNC machine to cut out a accurate hole to mount them and still look nice... See picture.... The wires come out the top of the board... See other picture... So when you mount it thru the plate. You need a couple washers to space it so it rests flat. If the wires were soldered to the other side of the board, this would not be an issue.Still would recommend
Larry S
2025-05-13 18:14:31
These are great little devices. I build various size battery packs and use these to determine their state of charge. The wide voltage range of 0-30v is perfect for my application They are very easy to use. If you don't need to measure
Aubrey Sheldon
2025-05-12 15:24:15
These work great. I have a very accurate digital multimeter and used it to check all 5 (powered from the same 5 volt source). They did not all read the same, but there is an adjustment potentiometer on the back (you need a very small flat blade or Phillips screwdriver to adjust) that allows you to easily calibrate the meter. Once this is done (or confirmed), the device holds calibration well. I won't hesitate to buy more of these if/when needed.
Joel Aycock
2025-04-16 16:06:05
Very nice. I measured only 0.05v error uncorrected at 12v (there is a pot to correct in case of larger error, but no correction was necessary in this case).Bright with little current draw- I measured only 10ma draw from my 12v battery (I tied white & red leads together so that the meter was powered from the battery being measured).Cheap & accurate, and quick delivery. What more could one want?
One of the guys
2025-04-02 14:15:02
Work perfect and the cost is excellent.
Eduard
2025-03-19 17:52:09
Solo eh probado 1 pero funciona a la perfección
Edgar Trujillo
2025-03-12 18:41:11
Fácil de conectar y usar, no estaba bien calibrado, pero es sencillo de ajustar.
Kunde
2025-01-13 12:46:13
Los productos llegaron a tiempo y corresponden a la información, estoy muy satisfecho y lo recomiendo encarecidamente.
Donald Hebig
2025-01-11 18:08:39
I disliked the false advertising and different product was shipped than what is advertised. It is missing the voltage calibration screw on the back.
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