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Attack of the Clones

Click to enlarge If you’ve been reading my articles (1, 2) on the Mindsensors PCF8574A board but are unable to purchase one for any number of reasons, here’s a blatant clone made on a breadboard.  It will function pretty much the same way as the Real Thing but doesn’t look nearly as nice.  Below you will find the schematic and the values of the components. The +5V’s in the circuit are all hooked up to pin 4 on the NXT connector.  Pin 1 on the connector is not connected to anything, it’s the analogue input for the NXT and we’re using I2C.  On the Mindsensors board C1 is a 22uF capacitor, however, I only had a 47uF.  I guess either will be fine.  Here is some source code to check if you’ve hooked it up properly: LINK.  It should blink the LED a few times a second.  The breadboard adapter is a home made one.  For instructions and more photos of that, click here.

Click to enlarge

R1, R2 82KOhm
R3 1KOhm
D1 10mA red LED
C1 47uF
C2 0.1uF


About Xander

Xander Soldaat is a Software Engineer and former Infrastructure Architect. He loves building and programming robots. He recently had the opportunity to turn his robotics hobby into his profession and has started working for Robomatter, the makers of ROBOTC and Robot Virtual Words.