Electrical engineer Bob Harbour has put a bit of contemporary usability spin on a classic piece of take a look at tools, including pc management and distant monitoring capabilities to a Nineteen Seventies digital load field.
“An digital load field is a device for engaged on energy provides. It offers a steady, adjustable load, turning energy into warmth,” Harbour explains. “I picked up an previous Transistor Gadgets DLR50-15-150 at a hamfest again in October for a really affordable value. This can be a fully analog instrument that may present a relentless present sink, a relentless resistance and form of a battery simulator. All of those configurations are adjusted with a knob on the entrance panel.”
Some reverse-engineering and a little bit of intelligent electronics design has introduced a classic load field out of the Nineteen Seventies and into the fashionable microcontroller period. (📷: Bob Harbour)
For the Nineteen Seventies, front-panel knobs and analog dials have been completely acceptable as a person interface. Trendy equivalents, although, provide distant configuration and monitoring capabilities lacking from classic gear — however somewhat than throw it out and purchase a contemporary alternative, Harbour determined to present the gadget a makeover whereas retaining as a lot of the unique machine’s innards as doable.
“A [Microchip] SAMD21E18 MCU [Microcontroller Unit] on a board of my very own design was used to regulate this venture,” Harbour explains. “A 16 character [by] two line LCD show is interfaced via the GPIO [General-Purpose Input/Output] pins. The person interface board can also be interfaced to the CPU through an I/O expander chip to the I2C bus.
“Isolating the person interface board is finished with an Analog Gadgets ADM3260 I2C isolator chip. Management voltage for the load field is managed by a 16-bit DAC [Digital to Analog Converter] whose output voltage is boosted with an op amp to the required 0 to 6V vary.”
The brand new {hardware} is housed in a secondary field connected to the highest of the unique. (📷: Bob Harbour)
The brand new {hardware} contains temperature probes and a USB to UART bridge for controlling the {hardware} from a distant system, utilizing an interface impressed by the Commonplace Instructions for Programmable Devices (SCPI) protocol. The brand new boards themselves are housed in a secondary field which sits atop the unique chassis, with the intention to protect the load field’s unique guts.
The complete venture write-up is accessible on Harbour’s Hackaday.io web page, together with schematics for the customized {hardware}.
