A LOGIC LEVEL DETECTOR
This project can be used to check the logic levels during logic gate experiments.
Connect the
croc clip to the zero volts rail and use the probe to check levels at various points. Red will come on if the level is high, and green if the level is low. If both leds come on, but dimly, then a high frequency pulse train is being detected. Construct the circuit on
stripboard and fit into a small
plastic box. Note that pins 7,8,9,12 and 13 of the CD4011 are all connected to the negative supply rail. Fit the leds and the on/off switch to the case and connect them to the stripboard with flex. Use a PP3 battery stuck in the box with double sided sticky tape, and fitted with a battery connector, . A probe can be constructed using a plastic Biro pen, with thick wire passing through it.