The fundamental of avometer is the magneto-electric dc ammeter that uses a delicacy (microamper is expressed) the head that make a list. Carry watch head when small electric current, can have voltaic directive. But watch head cannot carry big electricity, so, must in the paralell connection on watch head and series connection a few resistor undertake billabong or step-down, measure the electric current in giving circuit, voltage and resistance thereby. Introduce respectively below.
L measures principle of dc electric current. If graph 1a place is shown, shunt-wound on watch head a proper resistor (call billabong resistor) undertake billabong, with respect to span of OK and patulous electric current. The block of change billabong resistor is worth, can change electric current to measure range. L measures volts d.c. principle. If graph 1b place is shown, establish ties on watch head a proper resistor (cry times add resistance) undertake step-down, with respect to span of OK and patulous voltage. Change the times block cost that increases resistance, measure range with respect to what can change voltage.
L measures alternating voltage principle.
If graph 1c place is shown, because watch head is dc watch, when measuring communication so, need to add install and, cluster form half commutate circuit, the repass after having communication rectification becomes dc expresses a head, can measure alternating voltage so according to the size of dc. The method of span of patulous alternating voltage and volts d.c. span are similar.
L measures resistor principle.
If graph 1d place is shown, on watch head paralell connection is mixed the resistor with proper series connection, string together at the same time receive a batteries, make electric current is passed be measured resistor, according to voltaic size, measurable give resistance. The block of change billabong resistor is worth, with respect to the span that can change resistor.
The use of avometer
Avometer (with 105 model for exemple) if dial is right plan institute is shown. The knob that passes transfer switch will change measure project and measure span. Zero knob uses machinery to maintain pressing with a finger to be in still lie left null. "Ω " zero knob is to be used when measuring resistance, make pressing with a finger aims right null, measure numerical value in order to assure accurate.
The measurement of avometer limits is as follows:
LVolts d.c. : Divide 5 shelf, 0-6V; 0-30V; 0-150V; 0-300V; 0-600V.