

Master Reset line low sets all latches low via RESET diodes.
#LED LIGHT TABLE ONLY LIT IN ONE CORNER HOW TO#
This circuit may be used as a guide to how to do what you want using other means, probably. Warning: DO NOT let Olin see this diagram!!! Or, if you like, you can use the other output from each latch, the 2-input NAND gate, and drive the LED to ground (being careful to get the LED polarity right). If you decide to go with a CMOS family such as 74HC, this will still work. This is important if you decide to use 7400 or 74LS - those technologies do not source current well, but they sink current just fine. If you want to use discrete logic, such as 7400/74LS/74HC, etc, the total package count is 5 ICs - 1 7400, 2 7410 and 2 7411.ĮTA - You'll notice that the LEDs are driven by being pulled down, with current coming from VCC. Pushing any of Switches 1 - 4 will cause the corresponding LED to turn on, and disable any other switch activations by way of the AND gates. In the schematic, Switch 5 is a reset, and pressing it causes all 4 outputs (at the LED) to go high, turning off the LEDs. Simulate this circuit – Schematic created using CircuitLabįlip-flops can be synthesized from gates, although you may well decide to take Spehro's advice.
