AM1026 Preset Voltages

ARP 1026 Picture

Overview The ARP 1026 module was announced in 1970 but only a handful of production modules were produced, so it is very rare. It provides two channels of 8x control voltages the level of which is set by the front panel potentiometers and either manually gated on/off by the front panel momentary push button or by a set of 8x external control inputs.

There are indicator maps for each of the eight stages and it looks like ARP were intending to use LED’s rather than bulbs (finally). The 8x steps can be sequenced by the 1027 or 1050 clocks via an external RS232 cable at the rear of the modules, and this is typically how the 1026 was used as an expander module where it proves very useful in increasing the sequencer functionality of the ARP 2500.

ARP 1026 Modules

AM1026 Module There are no ARP schematics for the 1026 but the module uses a similar design approach to the 1027 and 1050. The momentary push buttons latch a flip flop which then activates the step position and drives the control potentiometers via transistor buffers. The external sequence input is buffered by Schmidt triggers and then drives the step position transistors via a digital OR circuit with the panel switches. The lamps are LED’s driven by transistors, to reduce power consumption of using bulbs.

The module has the following front panel controls:

  • 8x Channel I CV levels
  • 8x Channel 2 CV levels
  • 8x Momentary Switches

There are 10x 3.5mm jack sockets mounted at the base of the front panel:

  • 8x Step Gates In
  • 2x Control Voltage Outputs

Build Outcomes I played around with the idea in Spring 2017 and laid out the PCB’s in the Spring of 2019. I had purchased a large lot of 100k PRV6 potentiometers and had enough spare to use in the 1026. To reduce the amount of hand wiring I designed a front panel PCB that could hold the pots, and the LED’s and a round hole for the larger Switchcraft momentary switches. A second digital PCB is attached to the back with the CMOS logic on it.

Copyright AMSynths 2017