I'd like to use a momentary switch with a simple circuit (like the one below), that will illuminate two lamps for a short period (i.e. 10-20 seconds) with a single push.
Obviously 555 timers are popular for this kind of thing; and I've experimented with them a bit. But I'm currently examining a device that exhibits this general functionality; using only discrete components (mostly diodes, transistors, capacitors, and resistors).
How's this achieved without using a single integrated circuit?
The power supply is ~6.0V (4x ~1.5V AA batteries), and the initial load includes 2x ~3.0V lamps; in series.
Answer
Yes there are a few ways you can do this. One is to use a 555 timer but that will introduce a load on the batteries when it is off so will reduce the battery life.
A simple discrete solution with a mosfet would be something like this...
simulate this circuit – Schematic created using CircuitLab
Note it's cheap and dirty and lamps will dim out as the voltage on the gate approaches Vgs for the selected MOSFET. Chose a device with low Vgs threshold and Rds.
No comments:
Post a Comment