- Over rate components at least double, if you need a 1A-100V-100uS diode, use a 2A-200V-50uS diode.
- Unused CMOS inputs should have a pull up or pull down resistor, it should not float, or it oscillates.
- Have a decoupling capacitor 104 that is 0.1uF or 100nF across the supply of every IC very near the IC supply pins.
- A watchdog timer should be used in every microcomputer circuit like 8051 so that the system resets on hanging.
- The reset on a microcomputer should be applied till the supply to it is stabilized, this will enable a clean start.
- Use MFR (metal film resistor) 1% in all analog designs and if possible use only MFR for better reliability.
- Electrolytic capacitors have a shelf life, if you need to store them you have to charge them every month.
- If in your power supply you have a varistor, then you should have a fast acting fuse in series, as varistor fail as a short.
- The current thru a 3mm or 5mm LED (light emitting diode) should not exceed 20mA, 15mA is quite good.
- Analog ground (opamps), digital ground (CMOS) and power ground (relays and LED) should be separate, (linked at root)
- Pull up or pull down resistors in TTL can be 10K and in CMOS 100K and in battery operated systems 1M.
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