Main Features & Specifications
from nominal 12V DC, with low current drain: <50mA when relay is on, <5mA
when relay is off. Relay status indicated via a red LED.
via the contacts of a DPDT relay (ie, 2x normally closed, 2x normally open),
with 5A contact rating.
link selection for either a single ON timing period or continuous ON/OFF
and OFF times separately programmed via jumper links for any of 54 different
time periods; ie, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90
seconds, minutes or hours.
accuracy is ±1% at all settings.
be restarted at any time by pressing a reset pushbutton.
Module fits inside a
standard UB3 utility box.
In the March 1991 issue of "Electronics Australia", Rob Evans
presented the design for a "cheap and cheerful" electronic timer module called
the "Flexitimer". It could be programmed using a set of wire links and also by
changing the value of the timing oscillator components, over a range from a few
seconds to approximately one day. It could also be set for either one-shot or
continuous on-off cycling, although the on and off times were always the
This simple, low-cost circuit offered a great deal of timing
flexibility and as a result, it became extremely popular. An updated design was
published a few years later and the parts retailers sold kits of both this and
the original version for many years.
It was partly because of the popularity of the original
Flexitimer that we
subsequently developed the Programmable Flexitimer,
described in the August 2005 issue of SILICON CHIP. It was
based on a PIC16F84A microcontroller and was programmed rather like a microwave
oven, using a set of pushbuttons and a small LCD screen.
It worked well but in many ways it was "overkill". It was
rather expensive and as a result, it hasn’t been anywhere near as popular as the
Despite that, it’s clear that many people still want a timer
module that’s low in cost and just as easy to program as the original Flexitimer
but which offers even more flexibility. For example, many people want
independently programmable on and off times, as well as a considerably wider
range of programmable times for each.