US 8290398 A description fig1 illustrates a first embodiment of the present invention comparing that figure with fig1 of the sirasud patent numerous points of similarity will be observed including general layout resistance values and many common reference numerals reference may be made to that patent for particularities on elements of commonality preferred values for components shown in fig1 are listed in table i table i______________________________________ ref no resistance______________________________________ resistors r1 1 k u03c9 r2 220 k u03c9 r3 220 k u03c9 r4 820 k u03c9 r5 100 u03c9 r6 820 k u03c9 r7 470 k u03c9 r8 470 k u03c9 r9 220 k u03c9 r10 220 k u03c9 r11 220 k u03c9 r12 220 k u03c9 r13 20 u03c9 batteries b1 3 v b2 3 v______________________________________ referring now to fig1 the circuit of this embodiment has a red probe 18 and a black probe 28 for connection to a circuit not illustrated being tested a voltage indicator mechanism comprising a solenoid 103 is connected in series with a bilateral silicon switch q6 and connected between probes 18 28 the voltage indicator is conventional and is not illustrated herein very generally it has a spring which is opposed by solenoid 103 when q6 is conductive this happens when the potential across q6 is greater than a first predetermined value typically about eight volts under these conditions q6 presents a very low resistance and the voltage across probes 18 20 appears across the solenoid this moves the solenoid and stretches the spring thereby causing movement of a mechanical indicator however no voltage readings are indicated until the voltage across the probes reaches a second predetermined value which may range from about 80 to 90 volts voltage polarity is indicated by parallel red and.