Motive

Enoki have been using DMM PC510 by Sanwa for a long time. The PC510 usually measures current which has 0.2% reading accuracy.

Enoki would like to know another high accuracy current DMM.

Summary

Looking for DMMs, Enoki found that Sanwa PC7000 is less expensive and accurate.

Otherwise with low coefficient and less than 1Ω resistor, it is possible that a cheap DMM will be able to measure current with high accuracy.

Current fuse exchange

Enoki burnt 630 mA fuse that was peculiar for PC510 and removed it as shown in Photo1 and Photo2.

Photo1 burnt and new fuse

Photo2 630mA fuse holder

Dissipated battery exchange

Enoki exchanged 9V battery on 2021-12-25, which had been used since 2019-11-24.

The dissipated one lasted for 762 days.

Sanwa DMM current accuracy

Table1 shows Sanwa DMMs current accuracy and the prices^[1].

Table1 Sanwa DMMs current accuracy

Model	Accuracy [%]	Tilt stand	Price [JPY]
7000	0.1	NA	31,680
720M	0.2	NA	39,380
710	0.2	NA	23,320
773	0.5	OK	18,700

Few DMM tilt stands
Enoki puts PC510 side by side DSO on a self made shelf on desk. It is easy to read a value on LCD with tilt stand.

Should Enoki make a simple stand?

Bench top ammeter

Keysight and GW Instek sell high precision ammeter. But both are expensive.

Table2 shows the accuracy and prices^[2][3].

Table2 Bench top 1A accuracy

Model	Accuracy [%]	Maker	Price [JPY]
34460A	0.1	Keysight	137,383
PCS-1000	0.01	GW Instek	356,000

Result

Enoki would like to measure 1A range. Sanwa PC7000 may be the best choice for Enoki's usage.

Enoki's DMM PC510 high current measurement accuracy is rare even now.

Conclusion

If we can get low temperature coefficient resistor less than 1Ω, usual cheap DMMs may measure current at higher accuracy by measuring the resistor voltage drop.

Ref

[1] Sanwa digital multimeters
[2] PCS-1000 manual in Japanese
[3] 34460A specifications in Japanese