Testers or Instruments Electronic Circuits, beginning with L's

Tester or Instrumentation Circuits, Page 8a
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Last Updated on: Friday, March 12, 2010 12:07 PM

Circuits Designed by Dave Johnson, P.E. :

LASER/LED LIGHT OUTPUT INTENSITY METER
This circuit uses a large 1cm X 1cm silicon PIN photo diode and a transimpedance amplifier to measure the light power output of infrared and visible LEDs and laser diodes. It can be modified to produce almost any milliwatts to volts scale factor. It can be connected to either a multi-meter or an oscilloscope.

LIGHT RECEIVER WORKS FROM 1KHz TO OVER 70MHz
This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response. It is designed around a PIN photo diode that is packaged for use with plastic optical fibers. It can be used as an optical fiber receiver. By using the open end of the optical fiber it can "sniff" out any modulated light signals.

Low Value Capacitance Meter
This circuit was originally designed to measure the volume of fluid inside a medical syringe. As designed, it produces a zero to 5 volt output, corresponding to a capacitance change of about 10 picofarads. With a digital voltmeter, at its output, it can resolve a capacitance change of 0.002 picofarads or 2 femtofarads. (added 12/04)

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

LEE Test Fixture Instructions - AN-60-021 Application Note MiniCircuits.com (app note added 04/05/06)

Light Pollution Meter - LED brightness control circuit and a millimeter to compare light levels to LED level. (added 6/07)

Light Receiver works from 1kHz to over 70mhz - This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response. It is designed around a PIN photo diode that is packaged for use with plastic optical fibers. It can be used as an optical fiber receiver. By using the open end of the optical fiber it can "sniff" out any modulated light signals. ….(designed by David A. Johnson)

Light Sensor Adapter for Oscilloscope - (electronic schematic / circuit added 4/02)

Lightening Detector - A VLF receiver tuned to 300 kHz designed to detect the crackle of approaching lightning. A bright lamp flashes in synchrony with the lightning bolts indicating the proximity and intensity of the storm. It has a superior RF section with a single resonance near 300kHz and plenty of sensitivity. The antenna is a telescopic antenna that extends to two or three feet.... (added 5/05)

Lightning Activated Camera Shutter Trigger - This circuit is used to trigger a camera's electronic shutter circuit when a flash of lightning is present. This circuit would also work for photographing fireworks displays or other events involving flashes of light. (added 4/02)

Lightning Storm Detector - Reverse engineered schematic diagram of a mass produced lightning detector. The RF signal from lightning is quite strong and broad in spectrum so a tuned circuit is not required at the antenna input stage. Too much sensitivity will cause false alarms in a simple receiver such as this one. The circuit uses clever pulse timing and integration techniques ....(added 2/05)

Line Output/Flyback Transformer tester - This is a 'ringer'-type tester I (Bob Barker) originally designed for in-circuit testing of Line Output (Flyback) transformers in TVs and computer monitors. After a couple of technician-years of evaluation in actual servicing situations, it's also proved to be helpful in locating shorted diodes, capacitors and deflection yokes in horizontal deflection stages. LOPT/FBT condition is shown on an 8 LED 'bargraph' display. (schematic added 8/03)

Linear Resistance Meter - ….(electronic schematic added 08/08)

Linear wind power meter compensates for temperature - 11/13/08 EDN-Design Ideas: , Using a free-spinning anemometer for wind speed and a diode-connected transistor for temperature sensing, this meter measures the wind power available for "green" power generation.....(design idea added 08/09)

Live-line Detector - Detects the presence of a live mains conductor. Minimum parts counting. (electronic circuit added 06/07/08)

LM2675-5.0EVAL 1A Step-Down High-Efficiency SIMPLE Switcher Evaluation Board - The LM2675-5.0EVAL evaluation board is a fully-assembled and tested surface-mount regulator that provides a 5V±1.5% output at up to 1A, from an input of 8V to 40V. The overall efficiency is typically as high as 90%. The operating temperature range is 0°C to +85°C. (app note added 3/05)

LM2731/LM2733 Evaluation Board - This evaluation board demonstrates the operation of LM2731/LM2733 and gives information on their usage. The primary difference between the LM2731 and LM2733 is that the LM2731 has a higher current internal switch FET (with lower breakdown voltage), while the LM2733 has a higher voltage FET which handles less current. (app note added 3/05)

LM2750-5.0 Evaluation Board - This evaluation board demonstrates the operation of the LM2750-5.0 and gives information on it's usage. (app note added 3/05)

Load Pulser Tests Supply's Transient Response - 04/11/96 EDN-Design Ideas: Modern µPs place severe demands on the transient response of the power source. For example, Intel's P6 specification stipulates an output-current capability of at least 30A/µsec while maintaining output-voltage regulation within specified limits.....(design idea added 3/03)

Load Simulator Maintains Constant Power - 04/11/96 EDN-Design Ideas:.....(design idea added 3/03)

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