This general purpose, balanced triode voltmeter is stabilized by adjusting shunt resistors until the effective values of &mgr; andIpare the same for both tubes. Built‐in testing equipment is provided. The electrical zero of the galvanometer is unaffected by changes of ±20 percent in power‐supply voltage when the circuit has a d.c. sensitivity of 40,000 mm/volt. The tubes need not be specially selected. The balancing principle may be adapted for use in any circuit requiring matched tubes.