125KHZ Medium Power Ocsillator  -  This circuit is similar to MEDIUM POWER 125KHZ OSCILLATOR but adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz . . . [Hobby Circuit designed by Dave Johnson P.E.,  03/12/02]

125Khz Oscillator from CMOS Inverters  -  This circuit inverts the LC components so the inductor is grounded.  Two inverters are needed to produce the needed oscillation.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies . . . [Circuit by David A. Johnson P.E.,  03/12/02]

125khz Oscillator with Medium Power  -  This circuit adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz . . . [Hobby Circuit designed by David Johnson P.E.,  03/12/02]

125Khz Ultra Pure Sine Wave Signal Source  -  For some RFID systems operating at 125KHz, a very low distortion signal source reference is needed.  The circuit shown on this page produces a 10-volt peak-to-peak signal into a 50-ohm load, with a distortion of only 0.01% . . . [Hobby Circuit designed by David Johnson P.E.,  02/11/02]

200Mhz-400Mhz Voltage Controlled Oscillator (VCO)  -  If you need a clean emitter coupled logic (ECL) type signal between 200MHz and 400MHz this circuit works fine. It uses four voltage-controlled capacitors to change the frequency . . . [Circuit by David A. Johnson P.E.,  03/19/99]

3 Volt Low Battery Voltage Flasher  -  This circuit is designed to monitor two alkaline cells (3v) that form the battery often used in portable electronic equipment . . . [Circuit by David A. Johnson P.E.,  01/01/98]

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 . . . [Circuit by David A. Johnson P.E.,  06/17/00]

40Khz Burst Laser Diode Driver  -  Some laser tag or simulated combat games can use this circuit to send short bursts of modulated laser light at the opponent's vest, equipped with a matching light receiver. The circuit operates from three 1.5v cells (4.5v) that should provide enough energy . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/04/00]

40Khz LED Test Signal Generator  -  This 40KHz crystal controlled oscillator circuit drives an infrared LED with powerful 40ma pulses.  The circuit can be used to test optical communications circuits, designed to receive 40KHz modulated light signals . . . [Circuit by David Johnson P.E.,  02/14/02]

40Khz Precision Triangle Generator  -  This circuit generates a precision 40KHz triangle waveform . . . [Hobby Circuit designed by David A. Johnson P.E.,  07/09/06]

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.,  06/10/00]

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.,  12/18/04]

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.,  07/11/06]

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.,  06/17/00]

CMOS Inverter 125khz LC Oscillator  -  This circuit uses a single CMOS inverter to form a series resonant LC oscillator.  The values shown set the oscillation at about 125KHz but the other frequencies are possible by changing the main LC values . . . [Circuit by David Johnson P.E.,  03/12/02]

CMOS Inverter forms a Resonant LD Oscillator   -  This circuit uses a single CMOS inverter to form a series resonant LC oscillator.  The values shown set the oscillation at about 125KHz but the other frequencies are possible by changing the main LC values . . . [Hobby Circuit designed by David A. Johnson P.E.,  03/12/02]

CMOS Inverter Parallel LC Oscillator  -  I have used this parallel resonant LC oscillator circuit countless times.  The oscillator frequency is determined by the inductor and capacitor values.  I have shown an adjustable inductor to make it easy to set the frequency to a specific value . . . [Circuit by David A. Johnson P.E.,  03/12/02]

CMOS Inverters Form 125Khz Oscillator  -  This circuit inverts the LC components so the inductor is grounded.  Two inverters are needed to produce the needed oscillation.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies . . . [Hobby Circuit designed by David Johnson P.E.,  03/12/02]

CMOS Nand Gate Forms Gated 125Khz Oscillator  -  This circuit is uses a NAND gate as an inverter.  The gate allows the oscillator to be gated on and off.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies . . . [Circuit by Dave Johnson P.E.,  03/12/02]

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.,  06/03/00]

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.,  12/01/02]

Crystal Controlled 1KHz Signal Generator  -  A while back I got an email from a Discover Circuits visitor.  He needed a way to calibrate a RPM display for a big diesel engine.  The engine had a tachometer output which produced 12 pulses per rotation with an amplitude of about 5v RMS.  The full scale reading on the engine’s RPM speed display dial was 5,000 . . . [Circuit by David Johnson P.E.,  05/01/12]

ELC signal between 200Mhz-400Mhz  -  If you need a clean emitter coupled logic (ECL) type signal between 200MHz and 400MHz this circuit works fine. It uses four voltage-controlled capacitors to change the frequency . . . [Hobby Circuit designed by David Johnson P.E.,  03/19/99]

Flexible Outputs from Square Wave Driver  -  This circuit can produce an output signal ranging from DC to 100KHz. It can source a voltage ranging from 1v to 30v. It can sink a voltage ranging from zero volts to –30v. It can drive up to 200ma of current and can even be switched to a floating tristate . . . [Hobby Circuit designed by David Johnson P.E.,  07/08/00]

Gated 125Khz Oscillator  -  This circuit is uses a NAND gate as an inverter.  The gate allows the oscillator to be gated on and off.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies . . . [Hobby Circuit designed by Dave Johnson P.E.,  03/12/02]

Gated Crystal Oscillator with Very Low Power  -  The circuit gates the output of a continuously operating 32KHz crystal oscillator to the input of a C-MOS buffer when clock pulses are needed. The technique gets around the problem of a slow starting crystal oscillator by keeping the oscillator going and switching on a transistor power stage only as needed . . . [Hobby Circuit designed by David A. Johnson P.E.,  06/03/00]

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.,  05/29/00]

LC Oscillator Medium Power 125Khz  -  This circuit is similar to MEDIUM POWER 125KHZ OSCILLATOR but adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz . . . [Hobby Circuit designed by David Johnson P.E.,  03/12/02]

LED Test Signal Generator-40Khz  -  This 40KHz crystal controlled oscillator circuit drives an infrared LED with powerful 40ma pulses.  The circuit can be used to test optical communications circuits, designed to receive 40KHz modulated light signals . . . [Hobby Circuit designed by David A. Johnson P.E.,  02/14/02]

Light to Frequency Converter  -  This circuit uses a CMOS version of the classic 555 timer, to form a light intensity to frequency converter.  A small PIN photo diode is used as the light detector.  The pulses produced are short, so in some applications you may want to stretch them or . . . [Hobby Circuit designed by David A. Johnson P.E.,  05/04/08]

Low Battery Voltage Flasher  -  This circuit is designed to monitor two alkaline cells (3v) that from the battery often used in portable electronic equipment. It use an inexpensive IC from Panasonic that is connected to an efficient LED flashing circuit. When the battery voltage drops below a certain point the circuit flashes the LED. In the off state the circuit draws only 1uA, while in the active flashing state it draws 20uA.  . . . [Circuit by Dave Johnson P.E.,  01/01/98]

Low Frequency Oscillator draws only 2 Nanoamps  -  If you have hundreds of touch switches that need an excitation signal, then this circuit is what you need.  Its 20KHz 20v peak to peak output signal can supply up to 3 watts of touch switch excitation power . . . [Circuit by David Johnson P.E.,  07/11/06]

Low Power 100khz Light Receiver  -  By starving a high speed logic inverter for current, this circuit can produce a sensitive 100KHz light receiver circuit, which is immune to ambient light, but only drawing 100 micro amps from a 3 volt supply . . . [Circuit by David A. Johnson P.E.,  04/17/05]

Measure Button Battery Cell's Internal Resistance   -  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 . . . [Hobby Circuit designed by David Johnson P.E.,  07/11/06]

Medium Power 125khz Oscillator  -  This circuit adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz . . . [Circuit by David Johnson P.E.,  03/12/02]

Medium Power 125khz Oscillator #5  -  This circuit is similar to MEDIUM POWER 125KHZ OSCILLATOR but adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz. . . . [Circuit by Dave Johnson P.E.,  03/12/02]

Micro Power 40Khz Burst Laser Diode Driver  -  Some laser tag or simulated combat games can use this circuit to send short bursts of modulated laser light at the opponent's vest, equipped with a matching light receiver. The circuit operates from three 1.5v cells (4.5v) that should provide enough energy . . . [Circuit by Dave Johnson P.E.,  06/04/00]

Micro Power Over-Temperature Alarm  -  The circuit is powered for years by a single 3 volt lithium battery. It sounds an alarm when the temperature exceeds a certain point. With some minor changes the circuit could also be configured for an under temperature (freeze) alarm. The circuit uses a . . . [Circuit by Dave Johnson P.E.,  06/04/00]

Micropower 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 . . . [Circuit by Dave Johnson P.E.,  06/03/00]

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 . . . [Hobby Circuit designed by David A. Johnson P.E.,  09/04/11]

Octillator with Ultra Low Current  -  Here is a challenge.  Design an astable oscillator which draws only a few nanoamps of current from a +3v supply.  I gave this some thought and came up with the circuit below.  I used some pretty standard parts except for three surface mounted 1000M resist . . . [Hobby Circuit designed by David A. Johnson P.E.,  03/08/09]

Oscillator Draws 2 Nanoamps  -  If you have hundreds of touch switches that need an excitation signal, then this circuit is what you need.  Its 20KHz 20v peak to peak output signal can supply up to 3 watts of touch switch excitation power . . . [Hobby Circuit designed by David Johnson P.E.,  07/11/06]

Over-Temperature Micro-Power Alarm  -  The circuit is powered for years by a single 3 volt lithium battery. It sounds an alarm when the temperature exceeds a certain point. With some minor changes the circuit could also be configured for an under temperature (freeze) alarm. The circuit uses a . . . [Hobby Circuit designed by David Johnson P.E.,  06/04/00]

Parallel LC Oscillator with CMOS Inverter   -  I have used this parallel resonant LC oscillator circuit countless times.  The oscillator frequency is determined by the inductor and capacitor values.  I have shown an adjustable inductor to make it easy to set the frequency to a specific value . . . [Hobby Circuit designed by David A. Johnson P.E.,  03/12/02]

Precision 40Khz Triangle Generator  -  This circuit generates a precision 40KHz triangle waveform . . . [Circuit by Dave Johnson P.E.,  07/09/06]

Precision Ultra 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 . . . [Circuit by David A. Johnson P.E.,  05/29/00]

Ten-Second Ultra 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 . . . [Circuit by Dave Johnson P.E.,  05/29/00]

Triangle Signal Generator  -  A Discover Circuits visitor needed a variable low frequency triangle signal generator, which would produce a full 5 volts peak to peak signal using a 5v supply.  I suggested the circuit below.  It uses three rail to rail op amps (2 LMC6484 dual op amp packages) .  The first circuit produces a clean 2.5v reference voltage.  The second is configured as a classic multivibrator oscillator . . . [Hobby Circuit designed by David Johnson P.E.,  09/18/11]

Ultra Low Current Oscillator  -  Here is a challenge.  Design an astable oscillator which draws only a few nanoamps of current from a +3v supply.  I gave this some thought and came up with the circuit below.  I used some pretty standard parts except for three surface mounted 1000M resistors I had on hand.  The oscillator frequency measured a low 1Hz frequency and the average current was a very low 3 nanoamps.  If I had some higher resistors values handy, I think I could have gotten the current down below one nanoamp . . . [Circuit by David A. Johnson P.E.,  03/08/09]

Ultra Low Current Oscillator #4   -  The circuit below was inspired by a programmable unjunction transistor (PUJT) circuit sent to me by Karl Isbrecht.  In Karl’s circuit, the unijunction circuit made click sounds in a speaker and consumed very little power.  His circuit reminded me that a PU . . . [Circuit by David Johnson P.E.,  01/31/10]

Ultra Low Power 32Khz Crystal Oscillator  -  I have used this circuit many times when I needed a low frequency reference, which did not draw much power.  With the components show, the current from a 3v battery is less than 1.2 microamps . . . [Hobby Circuit designed by David Johnson P.E.,  12/18/04]

Ultra Low Power Astable 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 . . . [Circuit by Dave Johnson P.E.,  12/18/04]

Ultra 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. . . . [Circuit by David Johnson P.E.,  05/29/00]

Ultra Pure 125kHz Sine Wave Signal Source  -  For some RFID systems operating at 125KHz, a very low distortion signal source reference is needed.  The circuit shown on this page produces a 10-volt peak-to-peak signal into a 50-ohm load, with a distortion of only 0.01% . . . [Circuit by Dave Johnson P.E.,  02/11/02]

VCO from CMOS Schmitt Trigger IC  -  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 . . . [Hobby Circuit designed by David Johnson P.E.,  03/12/02]

Version 4 of a Ultra Low Current Oscillator  -  The circuit below was inspired by a programmable unjunction transistor (PUJT) circuit sent to me by Karl Isbrecht.  In Karl’s circuit, the unijunction circuit made click sounds in a speaker and consumed very little power.  His circuit reminded me that a PU . . . [Hobby Circuit designed by Dave Johnson P.E.,  01/31/10]

Very Low Power Astable Multivibrator  -  This classic circuit draws only 200 nanoamps from a 1.5v supply . . . [Circuit by David A. Johnson P.E.,  06/10/00]

Very Low Power Gated Crystal Oscillator  -  The circuit gates the output of a continuously operating 32KHz crystal oscillator to the input of a C-MOS buffer when clock pulses are needed. The technique gets around the problem of a slow starting crystal oscillator by keeping the oscillator going and switching on a transistor power stage only as needed . . . [Circuit by David A. Johnson P.E.,  06/03/00]

Very Low Voltage Oscillator Circuit  -  OK, you may not ever need an oscillator to function using a power supply voltage below one volt, but if you ever do need one, here is one way to do it.  Getting any electronic circuit to operate below one volt is a real challenge.  Typical silicon bipolar . . . [Hobby Circuit designed by Dave Johnson P.E.,  10/05/08]