Timers and
Counters Circuits, Page 4
Timers & Counters: #-A
B-E F-L
M-S T-Z
Last Updated on:
Tuesday, January 10, 2012 04:33 PM |
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Circuits Designed by Dave Johnson, P.E. : |
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Motorized Duck Decoy
Timer
I received a nice email from a duck hunter. He uses some motorized decoys to
lure ducks into his line of fire. However, the battery powered decoys only
have an on/off switch so once turned on; the decoy flaps its wings or paddles around
continuously. The hunter wanted a more realistic motion, which would power the
motor for say 10 seconds, then stop for another 10 seconds before starting up again.
The simple circuit below should work well for his application...
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On/Off Flip/flop Circuit with Automatic Timeout
This circuit is ideal when a device needs to be turned on and off with a single
pushbutton switch, but also needs to turn itself off after some period of time. With
the components shown, the output will stay on for only about 20 seconds.
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On/off Pushbutton Switch with 30 Minute
Timeout
I received an email
from a Discover Circuits visitor. He wanted to control power to a LED camping
light he was building. He wanted to turn the light on and off with a small
pushbutton switch. He also wanted a timer so the light would not stay on
longer than 30 minutes at a time. It seems that his kids often turned lights
on when going to bed and then forgot to turn them off.....
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Poor Man’s Digital Counter Using
Pedometer
There are many
occasions when you may want to count something electronically. Perhaps it is
car traffic on a street or items moving down an assembly line. It might be the
number of times a machine is activated or maybe you want to count the number of
people entering doorway. Commercial counting modules do exist but if you want
to use something cheaper, you can modify a pedometer to do much the same thing....
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Poor Man's Timer
Often during testing of certain equipment and components, you would like to keep
track of the elapsed time in hours, minutes and seconds. There are some nice
commercial digital timers and counters available for just this sort of application.
However, although it may not be as accurate, there is a cheaper way to go. I’m
sure many of you have some old wrist watches or battery powered dial faced alarm
clocks collecting dust in some drawer.
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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Machine Gun - This circuit produces a sound very similar to a
machine gun: |
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Metal Detector - This circuit detects metal and also magnets. When
a magnet is brought close to the 10mH choke, the output frequency changes.
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Missing Pulse Detectors / Negative Recovery Circuits - Uses the
LM555 timer or its cousins with other letter prefixes. There can be minor
differences between 555 timer IC's from different manufacturers but they all
should be useable for any circuit. Designed for Model Trains….
[from Rob Paisley's Model Train web site] |
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Model Lighthouse - This project was designed for a model
lighthouse to flash a lamp or LED in a simple sequence: two flashes of 2s
with a short gap of 1s, followed by a longer gap of 5s before repeating the
sequence. A 4017 counter is used to produce the flash sequence and this
project includes information on how to adapt it to give a different flash
sequence.... [Designed by John Hewes] |
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Model Railway Level Crossing Lights - The level crossing warning lights are
switched on automatically as a train approaches. First an amber light shows, then two
red lights flash until the train has passed the crossing.… [Designed by John Hewes] |
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Model Railway Signal - This signal is controlled automatically by a passing
train fitted with a magnet. It can also be manually set to red or green by pressing
the switches. Trains will automatically stop at the red signal.… [Designed by John
Hewes] |
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Model Railway Time - Here is a circuit that will convert any clock mechanism
into Model Railway Time. For those who enjoy model railways, the ultimate is to
have a fast clock to match the scale of the layout. This circuit will appear to
"make time fly" by turning the seconds.... |
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Monostable 555 - When the circuit is turned on, the output is LOW and a
brief negative pulse on pin 2 will make the output go HIGH for a period of time
determined by the value of R and C. If pin 2 is low for longer than this period, the
output will remain HIGH while pin 2 is LOW and immediately go LOW when pin 2 goes
HIGH.... |
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Morse Code Practice Oscillator - The speaker (LS) can be any 8-ohm type up
to 2-watts. C1 and C2 are ceramic capacitors. C3 is an electrolytic type. IC1 is a
CMOS MC1455P or equivalent. The cmos type consumes a lot less current when used with
the 9-volt battery, but if you don't want to spent the money then the LM555, NE555,
etc. are fine too and are pin-for-pin compatible with each other.... [Tony van Roon's
circuit] |
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Mosquito Repeller - This circuit produces a tone above the human audible
range and this is supposed to keep the mosquitoes away. You need a piezo diaphragm
that will respond to 15kHz and these are very difficult to find. |
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Motor PWM - The speed of a motor can be adjusted by this circuit, from 5% to
95%. |
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Motorized Duck Decoy Timer
- I received a nice
email from a duck hunter. He uses some motorized decoys to lure ducks into his
line of fire. However, the battery powered decoys only have an on/off switch so
once turned on; the decoy flaps its wings or paddles around continuously. The
hunter wanted a more realistic motion, which would power the motor for say 10 seconds,
then stop for another 10 seconds before starting up again. The simple circuit below
should work well for his application...[Circuit of the Week designed by David A.
Johnson, P.E.] |
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Music Box - This circuit produces 10 different tones and by selecting
suitable values to change the voltage on pin 5, the result can be quite pleasing.
Note: the two unused outputs of the 4017 produce a tone equal to that produced by the
555 when pin 5 has no external control voltage. |
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N' Steps And Stop Circuit (CD4017) - Uses the LM555 timer or its cousins
with other letter prefixes. There can be minor differences between 555 timer IC's from
different manufacturers but they all should be useable for any circuit.
Designed for Model Trains…. [from Rob Paisley's Model Train web site] |
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Negative Voltage - A negative supply can be produced by a "Charge-Pump"
circuit created with a 555, diodes and capacitors as shown in the following circuit.
The output will deliver about 50mA. |
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Network Lead Tester - This was designed for confirming the continuity and
correct wiring of computer network leads, but it can be adapted to check any lead with
up to 8 wires by using appropriate connectors.… [Designed by John Hewes] |
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