I need to trigger a 555 timer IC in astable mode as soon as it has power. It CAN NOT be done manually through a negative pulse like it usually is. The solution must be compact as space in my project is certainly at a premium. I either need a method of converting a constant high to a negative pulse, however this would require other components, or another method of triggering it. If neither are possible, is there an alternate astable IC I can use which would enable me to provide a 60s mark time followed by 1s space? Thanks in advance for your time, Regards, Eerf
60 s is too long a time for a old analog timer like the 555. Use a microcontroller.
This can be done by the cheap and tiny PIC 10F200. It has only 6 pins and comes in the same package individual transistors do. All it needs is power and a bypass cap. The oscillator is built in, which is good to a few percent. This solution will be smaller and take less power than a 555 timer, even if a 555 could reasonably do 60 s.
While what you need can be easily accomplished using a 555, in this instance - because of your space constraints - it seems a cheap 8 pin microcontroller might be a better fit.
In order to get the astable duty cycle you want, the 555 circuit will need two resistors and two capacitors and, if you need to use the bipolar for the highish source and sink currents its output can provide, the timing capacitor will be in the tens of microfarads for for an output high 60 seconds long.
A microcontroller will require, at the most, a power supply bypass capacitor and a ceramic resonator or crystal, or at the least, just the bypass cap if you choose one with an internal oscillator.