ARP 4001 Exponential Sub-Module

The 4001 was an encapsulated NPN-based exponential current generator (current source).

SCHEMATIC - (click on image to download full-sized version)


Resistors1/4 watt, 10%, carbon composite
10 KR4
15 KR5
1.5 MegR2
2.2 MegR3
Tempco Resistors1/4 watt, 3%, +3500ppm
100 OhmR1
1N4148CR1, CR2
TZ-81 *Q3
TZ-581 **Q4, Q5
TZ-81Q1, Q2 (matched pair)

* - TZ-81 alternate part was the 2N5249, also defunct. 2N3904 would be a modern equivalent.

** - TZ-581 alternate part was the 2N5367, also defunct. 2N3906 would be a modern equivalent.

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