Astable Multivibrator - The capacitor C charges via R1 and R2 and when the voltage on the capacitor reaches 2/3 of the supply, pin 6 detects this and pin 7 connects to 0v. The capacitor discharges through R2 until its voltage is 1/3 of the supply and pin 2 detects this and turns off pin 7 to repeat the cycle__ 555-Timer Astable Multivibrator - Scroll to find this circuit. This is an astable multivibrator circuits to alternately flash two LEDs. The R & C values determins. __ Designed by Bill Bowden
Astable Multivibrator - As shown in the schematic diagram here, the astable multivibrator simply extends the modification that converted the bistable multivibrator to a monostable version of the circuit. Now, both transistors are coupled to each other through capacitors. Whichever transistor __ Designed by Dr W D Phillips
Astable Multivibrator Gets Hysteresis From Positive-Feedback Stage - 22-Oct-09 EDN-Design Ideas - Add hysteresis through positive feedback Design by Robert Larson, Seattle, WA
Astable Multivibrator Lights LED From a Single Cell - 08/21/08 EDN-Design Ideas - A classical multivibrator drives a step-up inductor to power an LED from a single cell Design by Luca Bruno, ITIS Hensemberger, Monza, Lissone, Italy
Astable Multivibrator Projects - Astable or free-running multivibrators have been used in home-built amateur radio equipment for many years. The basic circuit is a two stage amplifier with AC-coupled feedback from output to input. One transistor stage is on (conducting current) __ Designed by Todd, VE7BPO
Astable Multivibrator with Very Low Power - This classic circuit draws only 200 nanoamps from a 1.5v supply . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000
Astable Multivibrators - Multivibrators: an old, well known and boring subject. No - not at all: there are lots of different ways of looking a them and they are not at all what they may seem. __ Designed by Richard Torrens
Astable Ultra Low Power Multivibrator - Taking advantage of some new voltage comparators, this circuit can produce a nice square wave signal while drawing only 1.6 micro amps. With the inclusion of a diode, the circuit can also produce short pulses instead of a square wave signal . . . Hobby Circuit designed by David Johnson P.E.-December, 2004
Button Battery Cell Internal Resistance Measurement Circuit - The open cell voltage of a small silver oxide button cell battery remains very close to 1.5 volts over most of the life of the cell. However, there is a relationship between battery health and the internal resistance of the cell. This circuit when used. . . Circuit by Dave Johnson P.E.-July, 2006
Cheap Low Power 3v 2hz Oscillator - This is yet another method to generate low frequency output pulses. The circuit uses an inexpensive under-voltage monitor IC and a couple of cheap MOSFETs. It could easily be modified to produce pulse frequencies from about one cycle per minute to a maxim . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
CMOS
Oscillator, Draws Only 0.5ua - If truly low power oscillators interest you, this circuit draws a mere 2 microwatts (500nA) from a 6v battery. It uses a very inexpensive C-MOS IC to produce a frequency of 2Hz. However, by changing the component values you can push it to 300Hz . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000
CMOS
Schmitt Trigger IC Makes VCO - By changing the supply voltage fed to a classic 4584 Schmitt trigger type oscillator, the oscillator frequency can be changed over a range of 50:1. A 74HCU04 inverter is used at the output of the 4584 to maintain a constant TTL logic level signal. . . Circuit by David Johnson P.E.-December, 2002
Dummy Alarm - This project makes a superbright LED flash briefly once every 5 seconds to imitate the indicator light of a real alarm. The circuit is designed to use very little current to prolong battery life so that it can be left on permanently. This is a simple project, ideal for a beginner __ Designed by John Hewes
Eight LEDs Random Flasher - This project uses a 4026 counter and display driver IC to flash eight LEDs in an apparently random manner. It can be used to create a display of your choice. __ Designed by John Hewes
Flashing LED - This simple project makes a good low-cost first project to check your soldering skills and learn to identify common components. The LED flashes at about 3Hz (3 flashes per second). __ Designed by John Hewes
Flip Flop - In this project we examine one of the most valuable circuits to be invented, the flip flop. Originally it was designed with VALVES, along with its simpler version (without the two capacitors, called a bi-stable Multivibrator) , it was realised it __ Contact Colin Mitchelltalking @ tpg.com.au
Flip Flop Flashers Buzzers Etc - Several circuits here. The familiar astable flip-flop circuit is a handy configuration for making flashers or generating squarewaves. Here is a typical alternating LED flasher with the LEDs in the emitters instead of collectors as is normally done. The bias resistors are directly connected __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Heart-shaped Badge - The badge consists of eight LEDs arranged in the shape of a heart. One LED is lit at a time and this 'chases' round the shape. It would be easy to adapt this project to create other shapes with the eight LEDs. __ Designed by John Hewes
Highly Stable Lower Power Oscillator - This circuit works much like the classic 555 timer, but draws only about 1.5 microamps from a 3 volt battery. It is highly stable under varying temperature and supply voltages. . . . Hobby Circuit designed by David A. Johnson P.E.-May, 2000 |