AUTO RETRY fOR MAX1637 STEP DOWN CONTROLLER ELECTRONIC DIAGRAM

AUTO RETRY fOR MAX1637 STEP-DOWN CONTROLLER ELECTRONIC DIAGRAM

On microprocessor supervisor (IC1), an internal power-fail comparator and manual-reset circuitry (MR) is included. IC1s PFI input will detect when Vout(1.8V) is above the internal reference voltage (1.25V). Active-low RESET and active-low SHDN go high after a timeout delay of 140ms, re-enabling IC2. The other way to re-enabling IC2 is when the supply voltage is first switched on : the 3.5V rail stabilizes after 140ms will cause active-low RST to go high and activate IC2.The active-low PFO output produces a pulse using the internal 60k pull-up resistor and external 0.1 uF capacitor if Vout falls below 1.25V (due to a short circuit, for instance).

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DC Motor Speed Controller

This circuit takes benefit of the voltage drop across bridge rectifier diodes to provide a 5-position variable voltage supply to a DC fan or other small DC motor. It is not as environment friendly as a change-mode circuit but it has the advantages of simplicity and no swaping hash. The 4 full-wave bridges are linked so that every has two pairs of sequence diodes in parallel, giving a voltage drop of about 1.4V, relying on the burden present.

Circuit diagram:

DC Motor Speed Controller Circuit Diagram

The rotary swap should have \"make before break\" contacts which will have to be rated to take presents as a lot as about an amp or so. For better currents, better rated bridge rectifiers and a suitably rugged rotary swap (or solenoids) will most definitely be required. If you want to have smaller voltage steps, that you must use the commoned AC inputs on the bridge rectifiers to provide intermediate steps on the velocity swap.

Author: Stephen Butcher,

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