EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: technix on May 15, 2015, 05:41:11 pm
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The last post somehow exposed a bug in the forum software and does not load... :-\
This is a dummy load, with Arduino-compatible microcontroller control.
The analog section is identical to the design used by Dave, but the load resistor is 0.1 ohms instead of 1 ohm, in order to lower the voltage drop across the load resistor to allow 5V operation. The load transistor is IRL540N, for its lower threshold voltage, also to enable 5V operation. The smaller load resistor also means lower sense voltage. Hence a sense preamplifier is added. This have to be an RRIO amp. In the schematic I used LMV358 but TLC2272 can be used too, probably some other model too. MC1403 is used as the internal reference, which is shared by the analog and digital sections. The adjustment is carried out using a MCP41010 d-pot.
The digital section handles controlling the analog section with an ATmega328P microcontroller, and a human interface based on a 16x2 character LCD and 5 buttons. A USB interface based on CH340G exist too to allow both remote controlling and firmware updating. The firmware update mode is compatible with Arduino.