Bob Parker's Blue2 ESR meter

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Got this one today and I did a first evaluation along with some DER-EE LCR meter comparison readings. I thought it might be of interest to some of you too. Although little obscure still, its the modern version of Bob Parker's classic in-circuit ESR meter. He redesigned it in 2019 but it started becoming available much later due to the pandemic's disruptions.

This time its of SMD construction with a faster and less power consuming processor. Has captive RG-174 test leads terminated with DMM style sharp point probes. 70cm long from case to tip. There is no zeroing function, no need to delta out the leads resistance due to Kelvin wiring. Two segmented LEDs show value and two simple ones are used for dots. When one dot is lit we are reading in Ohms. When two dots are lit we are in its mΩ displaying range. Dash is on/OL. Housed in a Hammond translucent blue case with over-molded rubbery sides. 11.5x8x2.5cm. Seems rugged enough. Has just one mini push-button, top left located and recessed. For on/off. Will also auto off when left unused for five minutes. Works on two AA batteries.

I found it is rapidly and securely settling for readings. Either for board populated or for free capacitors. It gives dependable ESR results especially in the mΩ range for large electrolytic capacitors (<0.1Ω). Also accurate on tiny value emitter power output or shunt current measuring resistors. I saw on the scope that it uses a 5 uS positive pulse as test signal.
Around 47uF and below, as its 1uF spec limit is progressively approached, it tends to over-read ESR. Surely starts blending some capacitive reactance. Regardless of absolute ESR, the readings even for <10uF values were compatible to those advised on the meter's face sticker for good cap/bad cap fast decisions.

For the little time I used it I believe its a very practical surefooted meter with service work ergonomics in mind. Makes the bad cap hunting job quicker. I would only like bit more supple leads and a kick stand. Of course in the heart of it its just a specialized 0.001Ω-99Ω impedance meter and it should not be used for capacitors characterization work like a fully fledged LCR meter.


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For completeness, some measurements on larger size capacitors also.
Columns from left to right represent: Value, type, ESR on Blue2, ESR on DER-EE 100kHz sinewave Rs mode.

2200uF/100VElna For Audio0.0160.012
3300uF/50VSamwha SG0.0150.007
4700uF/35VSamwha HM0.0900.086
2200uF/100VNippon SMH0.0250.020
10000uF/63VF&T GS 4pin0.0200.017
22000uF/25VNippon SMH0.0110.006
47uF/400VNippon SME0.310.237
330uF/250VNichicon LK0.0860.067
330uF/350VDaewoo CE-LSS0.190.172


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If your meter has user-selectable test frequency, and if it also will display impedance, then you might be able to measure the equivalent series inductance of large electrolytic capacitors. Use the meter to find the capacitor's self resonant frequency, where impedance is a local minimum. Now you know C and you know f_resonant, so you're able to calculate ESL.

For the electrolytics I played with, 470uF to 2200uF, self resonant frequency was between 30 and 100 kHz.