125Khz LC Oscillator
This circuit adds more invertors in parallel to deliver more power. It is similar to CMOS
INVERTERS FORM 125KHZ OSCILLATOR. Please note that the values shown are for 125KHz.. . . Circuit by Dave Johnson P.E.-March, 2002
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 David Johnson P.E.-March, 2002
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 Johnson P.E.-March, 2002
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 A. Johnson P.E.-March, 2002
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 Dave Johnson P.E.-February, 2002
12v Touch Switch Exciter Circuit
This circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits. It can support a cable length of about 2500 feet. A typical remote switch circuit is also shown as well as a receiver circuit for those switches.. . . Circuit by Dave Johnson P.E.-February, 2002
20 LED Night Light - After 3 years of continuous 24/7 operation I noticed that the 20 LED array I was using as a night light next to my back door was fading. Some of the LEDs were much dimmer than others. I figured that over time, the internal heat dissipated from the LED chip was causing the LED light intensity to fade. I decided it was time to replace the light. . . . Circuit by David Johnson P.E.-July, 2017
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 Dave Johnson P.E.-March, 1999
24v NiMH
Battery Charger using a 12v Solar Panel
A while back I received an email from a guy in the UK. He wanted to use a small solar panel, designed to charge 12v lead acid batteries, but use it to charge a 24v battery pack. His 24v battery pack used 20 AA size NiMH
cells. He went on to explain that his 20 cell NiMH
battery pack was used very infrequently . . . Hobby Circuit designed by Dave Johnson P.E.-October, 2011
28V Dual Tracking Bipolar Supply with Outputs from ±5V to ±25V
The LTC3260 is a low noise dual polarity output power supply that includes an inverting charge pump with both positive and negative LDO regulators. The charge pump operates over a wide 4.5V to 32V input range and can deliver up to 100mA of output current. Each LDO regulator can provide up to 50mA of output current. The negative LDO post regulator is powered from the charge pump output. The LDO output voltages can be adjusted using external resistor dividers___ Linear Technology/Analog Devices App Note, Apr 19th 2012
300v Peak to Peak Signal Generator
This circuit converts a square wave signal to a +-150 volt output signal with fast 100nS rise and fall times. . . Circuit by David A. Johnson P.E.-June, 2000
5V power supply teams low-dropout regulator, charge pump
8-Jan-04 EDN-Design Ideas Auxiliary power of 3.3V is replacing the 5V auxiliary power that "silver boxes" supply in most computer systems, but some circuits still require a 5V supply. Such systems impose the messy task of creating a central 5V auxiliary supply from the 3.3V auxiliary supply and then routing 5V power throughout the motherboard__ Circuit Design by Jim Christensen, Maxim Integrated Products, Sunnyvale, CA
Astable Multivibrator with Very Low Power
This classic circuit draws only 200 nanoamps from a 1.5v supply . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
Astable Multivibrators
Multivibrators: an old, well known and boring subject. Nonot 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
Audio Frequency Digital Noise Generator
When you need to test an audio circuit with broadband noise, this circuit works great. It uses just three inexpensive C-MOS ICs that generate a series of output pulses whose widths vary randomly. I included a level control pot. . . Circuit by Dave Johnson P.E.-July, 2000
Boost converter generates three analog rails
EDN-Design Ideas July 2, 1998 [ NOTE
: File has multiple design, scroll for this one.] The standard boost converter in Figure 1 uses not only IC1, C1, L1, D1, and C2 to generate a main 5V output, but also additional small, low-cost components to provide two auxiliary supply rails of 10 and -5V. These auxiliary outputs are useful for analog circuitry in small handheld instruments, which often require supply voltages greater than the signal range. Input voltages of 0.8 to 5.5V, which is equivalent to voltages from a battery pack of one to three cells, sustain the main regulated output of 5V±2%. With an input of 1.8V from two flat cells, for instance, and with the other rails unloaded, the circuit can produce 25 mA with 80 to 90% efficiency.__ Circuit Design by Tim Herklots, Maxim Integrated Products Ltd, Theale Berkshire, UK
Build a charge pump with ultralow quiescent current
5-Aug-04 EDN-Design Ideas Portable battery-powered devices often spend most of their life in standby mode, in which the quiescent current of an internal boost converter continuously bleeds the battery. The quiescent current during standby can be larger than the actual load current. Though several inductor-based converters offer maximum quiescent current of less than 10 µA, designers usually prefer or require a regu__ Circuit Design by Greg Sutterlin, Maxim Integrated Products, Sunnyvale, CA |