HoldPeak’s HP-770D is a 40,000 counts true RMS multimeter. Price and size-wise it is very similar to UNI-T’s new UT61E+ I reviewed a while ago. Although HoldPeak is not as well known as UNI-T, this meter does offer some advantages compared to the UT61E+ in some areas besides its higher counts (40,000 versus 22,000 for UT61E+).

In its 40mV range (for both AC and DC) for instance, it can measure with a resolution of 1μV, whereas UT61E+ only has a resolution of 10μV. For some electronics hobbyists, especially for those who do low level measurements routinely, this is a welcome feature and seldomly found on meters of this price range.

One feature I like a lot about this feature is its interlocked input design. A “shutter” mechanically blocks the jacks that are not allowed by the range currently dialed in. In my opinion, this design is superior than other designs (e.g. visual/audible warnings) that I have seen. Another feature that is unique to this meter is its automatic back light. There is a CdS photo sensor that detects the ambient light, when the environment gets dark the back light would turn on automatically.

The absolute accuracy of this meter is not as tight as that of the UT61E+ however, but it’s nevertheless adequate. Interestingly though, the product page does not give any detailed specifications. The specifications listed below are copied from the manual for your reference:

DC Voltage

RangeResolutionAccuracy
40 mV1 μV±(0.5% of rdg + 5 digits)
400 mV10 μV±(0.1% of rdg + 2 digits)
4 V100 μV
40 V1 mV
400 V10 mV
1000 V100 mV±(0.1% or rdg + 5 digits)

AC Voltage (True RMS)

RangeResolutionAccuracy
40 mV1 μV±(1.0% of rdg + 10 digits)
400 mV10 μV±(0.8% of rdg + 10 digits)
4 V100 μV
40 V1 mV
400 V10 mV
750 V100 mV±(1.2% of rdg + 10 digits)

Impedance: 10MΩ, >100MΩ on 40mV/400mV range

Overload protection: 1000V DC or 750V AC rms

DC Current

RangeResolutionAccuracy
400 μA0.01 μA±(1.0% of rdg + 10 digits)
4000 μA0.1 μA
40 mA1 μA
400 mA10 μA
4 A100 μA±(1.2% of rdg + 10 digits)
20 A1 mA

AC Current (True RMS)

RangeResolutionAccuracy
400 μA0.01 μA±(1.2% of rdg + 10 digits)
4000 μA0.1 μA
40 mA1 μA
400 mA10 μA
4 A100 μA±(1.5% of rdg + 10 digits)
20 A1 mA

Overload protection: 500mA/500V fast-blown fuse, 20A/500V fast-blown fuse, 20A up to 15 seconds

Frequency range: 40 to 1 kHz

Resistance

RangeResolutionAccuracy
400 Ω0.01 Ω±(1.0% of rdg + 10 digits)
4 kΩ0.1 Ω±(0.5% of rdg + 10 digits)
40 kΩ1 Ω
400 kΩ10 Ω
4 MΩ100 Ω
40 MΩ1 kΩ±(1.0% of rdg + 10 digits)

Overload Protection: 500V DC or AC rms

Capacitance

RangeResolutionAccuracy
99.99 nF10 pF±(3.0% of rdg + 10 digits)
999.9 nF100 pF±(2.5% of rdg + 5 digits)
9.999 μF1 nF
99.99 μF10 nF±(5.0% of rdg + 10 digits)
999.9 μF100 nF±(10.0% of rdg + 20 digits)
9.999 mF1 μF
99.99 mF10 μF

Overload Protection: 500V DC or AC rms

Frequency

RangeResolutionAccuracy
9.999 Hz0.001 Hz±(0.1% of rdg + 5 digits)
99.99 Hz0.01 Hz
999.9 Hz0.1 Hz
9.999 kHz1 Hz
99.99 kHz10 Hz
999.9 kHz100 Hz
9.999 MHz1 kHz

Sensitivity: sine wave 0.6V rms (9.999MHz: 1.5V rms)

Overload Protection: 500V DC or AC rms

One drawback of this meter is the resolution in its lowest capacitance measurement range (99.99nF). In this range, it unfortunately only has a resolution of 10 pF, instead of the 1 pF commonly found on other meters in similar class. The temperature measurement range has a 0.1 degree resolution, which is better than most meters I have seen. Also to note is that although not specified, the display update rate is adequate in most ranges.

The meter operates on a 9V battery. The current consumption is at around 5mA depending on the range (with the back light off), which is quite decent. The meter utilizes a Holtek HT7530-1 3V low dropout linear regulator for the regulated voltage. This means that the meter can technically function with the supply voltage all the way down to just above 3V. Although the low battery indicator would come on when the supply voltage drops below 8.5V.

Another disappointment is the lack of adequate input protection. Besides a lone PTC, there is no MOVs to be seen. Since there is no MOVs to absorb any transient it is highly doubtful that this meter meets the CAT III rating that is stamped on the case.

Here is a close up of the circuit board. A Hycon technology’s HY11P14 mixed signal microcontroller is used to drive the LCD. The chip also has a built in 18-bit ADC. The main DMM chip used is an HY3131. It’s a 50,000 count DMM chip and has a 24-bit ADC built in. There is a 2K 2402A EEPROM on the circuit board, it is presumably used to store calibration and/or configuration data. A jumper labeled SW1 can also be seen below, I think it might be used to enable calibration.

You can find the detailed review video below:

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