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Telephone FM Transmitter - This FM transmitter attaches in
series to one of your phone lines. When there is a signal on the line
(that is, when you pick up the handset) the circuit will transmit the
conversation. In particular it will radiate from the phone line itself. It
is a passive device, there is no battery. It uses the signal on the phone
line for power.….....
Tester Checks Christmas Tree Lights - 12/23/99 EDN on Components
Why is it that you always test 48 bulbs before you find the bad one in a
50-light string?This simple circuit allows you to divide and conquer,
greatly reducing the time it takes to find the bad bulb…. [Design Idea by
William Dias, Brown&Sharpe, North Kingstown, RI]
Third Brake Light Pulser - Several years ago these flashers were
introduced in the automotive industry as part of the third brake light and
contained strobe lights (and strobing continuously for the duration of
pressing the break pedal) but got abandoned almost immediately sometime
later because of the 'strobe' effect it has on some people..... [Tony van
Roon's circuit]
Timer Exploits OpAmp Bias Current - 07/21/94 EDN-Design Ideas.....The
simple, low-cost analog timer in Fig 1 exploits the parasitic input-bias current of
op-amp IC1. The timer achieves long time delays even though it uses only low-value,
inexpensive ceramic chip capacitors. After all, because the input-bias current is the
minimum current flow into an op amp,..... [Design Idea by Aleksandr Belousov,
Baltimore, MD]
Timer light switch-Digital - Typical circuit representative of those used in
most light switch type digital timers. The timer module is normally a PIC or custom
chip, and it syncs to the AC line so that a trigger pulse can be supplied at the right
moment….schematic only…. [Circuit by Stepan Novotill]
Touch Activated Lamp - The circuits below light a 20 watt lamp when the
contacts are touched and the skin resistance is about 2 Megs or less. The circuit on
the left uses a power MOSFET which turns on when the voltage between the source and
gate is around 6 volts. The gate of the MOSFET draws no current so the voltage.....
[Bill Bowden's circuit]
Traffic Light Control Circuit 74145 - This page features a circuit that has
twenty open collector outputs that turn on one at a time in a continuous sequential
manner. The circuit make use of the 74LSxx family of TTL integrated logic devices. The
circuits… [from Rob Paisley's Model Train web site]
