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I can pretty much guarantee that there is nothing here that you're likely to just happen to be interested in. But a search engine should find it if needed. :)
Pin 1: 300 ohms to Gnd (for DPs) Pin A: NC Pin 2: NC Pin B: DP3 - Connect to Pin 1 (188.8) Pin 3: NC Pin C: DP2 - Connect to Pin 1 (18.88) Pin 4: NC Pin D: DP1 - Connect to Pin 1 (1.888) * Pin 5: In- Pin E: NC Pin 6: NC Pin F: NC Pin 7: NC Pin H: In+ Pin 8: LED Digit Power Pin J: NC Pin 9: Vdd (+5) Pin K: Gnd Pin 10: LED Sign (+/-) Power Pin L: Gnd
Range: Set to +/-1.999 VDC, DP1 selected by being connected to pin 1.
IC info; ICL7107R, datasheet at: Intersil ICL7107 Datasheet.
U.S. Patent #2,975,330: Electrodeless Discharge Method and Apparatus shows the basic idea though the actual implementation is differs considerably.
Filament: 5 V results in a nice orange glow and it works, but I don't know if it's really rated for 6.3 V.
B+: 150 to 300 VDC to the case. There is some voltage threshold above which the glow inside the globe gets noticeably more intense, though it's never what one might call bright.
If anyone knows more about these devices, please contact me via the Sci.Electronics.Repair FAQ Email Links Page.
I have determined operation by tracing the wiring of the 4 pin connector and then measuring the output voltages. For the measurements, Output #1 was set for 12 kV.
Pin Function Value
------------------------------
Red Output 1 +12 kVDC
White Output 2 +6 kVDC
1 Output 3 +625 VDC
2 DC In +24 VDC
3 Output 4 -125 VDC
4 Common
The output current capability is knnown but not it's certainly not very high.
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