OK, I have a 12V DC system that once it turns on, I need a secondary part to turn on roughly 30 seconds later. I was thinking an edge triggered 555 timer like the diagram I have here in my trusty book. The secondary system is already on a relay, but taxes the battery as it takes a ton of juice to get it going. (This is basically a gas engine powered/generator/air compressor). The problem is that as soon as I try to start the engine, the electric air compressors try to run immediately taking all my cranking power. If the engine was allowed to start, and stabilize for 30 seconds and get recharging before the electric air compressors kicked on, it would solve my no start issue that happens too often. And unplugging the air compressors everytime is obviously a pain in the a**. I have it all figured out, but I do not have the 1N914 diodes right now (I have ordered 500 of them to add to my bins). Is there a suitable standard diode that can be substituted, or is there another way to do an edge triggered 555 that I am missing?