This is a battery powered one hand holdable universal LCR bridge. It operates at 1 kHz.
There is a provision for External AC drive as well as external DC bias, which is why I got this instrument. So that I can make some measurements on the PNI Magneto-Inductive (MI) sensors.
The only way to power the bridge is by means of a 9 Volt battery, not the normal type but a larger Eveready 276.
The ground side of the 1/4" mono phone jack for "Bias" is connected directly to the "Hi" DUT terminal.
The center of the 1/4" jack is connected to the Det + ve" terminal through a 1,000 Ohm resistor. The limit on bias current translates into a voltage limit at the jack.
DC bias is only active when in the L, C or R function positions and in the D mode and no change with position.
PNI SEN-L DataWith no bias applied the inductance looks like 102 mH and there is no change in inductance with magnetic bearing.
With 15 Volts (15 mA) DC bias the inductance reduces to 100 mH and changes about 1 mH with position.
Using the R int DC function switch setting results in a DE resistance reading of 120 Ohms.
Using the R function switch position ( 1 kHz gives 116 Ohms.
With 1.0 Volt DC bias the inductance is about 102.2 mH. D = 5.2 (X1 D range) This is closer to where the sensor should be biased.
With the coil pointing up the inductance is about 104 mH.
The normal frequency of operation for this coil is closer to 59 k Hz, so the 1 kHz TF-2700 frequency may be too low for good sensitivity
Using the Ext AC input may allow much more sensitivity. How to use it?
L C R 10 uH 1000 uF 1 100 uH 100 uF 10 1 mH 10 uF 100 10 mH 1 uF 1000 100 mH 0.1 uF 10 k 1 H 10,000 pF 100 k 10 H 1000 pF 1 M 100 H 100 pF 10 M
Discrete components and point to point wiring plus a single sided PCB.Back to Brooke's Test Equipment, Military Information, Home page
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