I found this latching circuit on Stack Exchange. This makes up the left side of the above schematic. I've already tested the latching circuit and it works great. Basically, it lets you use a momentary switch to turn on an ATX power supply.
Being that I'm going with a 74'04, I will have a bunch of unused NOT gates. So I came up with an idea to use them to control some LED status lights. This makes up the right side of the schematic. Basically, I have the anode of both LEDs connected to the +5v signal. The cathode of each LED is connected to the output of a NOT gate. The PS_ON signal starts high, and it latched low when the momentary switch is pressed. So using the PS_ON signal, I'm controlling which LED is pulled low and turning on, with the other being pulled high. For some reason I thought this would be better than the reverse, connecting the cathode of each LED to ground and the anodes to the NOT gates and driving them with a high signal. Does it make a difference?
The way I have it now works fine when I simulated it in Tinkercad, but that doesn't mean it's safe or best practice to use the 74 part in this way. Are there any issues in my design?
Should I use an HC part instead of LS? I've read that the 74HC has an output drive current of about 25mA, where as the LS is much lower.
Statistics: Posted by Ziggy587 — Sun Jul 28, 2024 8:58 am — Replies 1 — Views 15