Testers or Instruments Electronic Circuits, beginning with Q-R

Tester or Instrumentation Circuits, Page 11a
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Last Updated on: Friday, March 12, 2010 12:07 PM

Circuits Designed by Dave Johnson, P.E. :

RS232 Data Bus Status Indicator
This circuit indicates TXD and RXD activity. The thresholds are set at plus 3 volts and minus 3 volts. (added 12/04)

RS232 Serial Interface Status Indicator
I designed this circuit many years ago and have used it several times since. It uses a single logic IC to indicate the TXD and RXD line activity of a typical RS-232 serial data communications link. The thresholds are set at plus 3 volts and minus 3 volts. Two dual color LEDs are used as indicator lights.

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

Resistance, DC Current, AC Current, Frequency and Period Measurement Errors in DMMs 5988-5512EN - Aligent Application Note (app note added 4/08)

Resistor Decade Box - (schematic / circuit added 6/07)

Revolution Meter - Revolution meter by measuring method of strobe synchronization. It can measure up to 100,000 rpm in two ranges. (added 6/06)

RF Power Meter - Here is a simple set up which will enable them to measure the out put power of their transmitter. All that they require is a good multimeter which has a sensitivety of 20k ohms/4 Watts which is adequate for low power transmitters. (electronic circuit added 9/04)

RF Power Meter - RF Power Meter for QRPers (electronic circuit added 03/04/05)

RF Power Meter for the QRPer - (electronic design / schematic added 2/05)

RF Probe - Use this probe with any transmitter for tuning. Connect the probe at the output of each stage and tune till maximum DC voltage appear on Digital Voltmeter. (added 11/05)

Ring oscillator measures cable length - 05/12/94 EDN-Design Ideas: In Fig 1, an ECL exclusive-NOR gate (F100107) and a length of cable form a simple ring oscillator. The delay from the cable and the gate determine the ring oscillator’s frequency. A 100m cable yields approximately a 600-MHz oscillation frequency. The gate’s second output connects to a frequency counter. (design idea added 09/05)

RMS Calculations for Energy Meter Applications Using the ADE7756 - AN-578 Analog Devices Application Notes (app note added 6/06) The document describes the implementation of an rms signal processing algorithm using the ADE7756 and a Microcontroller (PIC16C63) from Microchip.

RMS to DC Converter is Accurate and Stable - 09/14/95 EDN-Design Ideas: Combining the well-known true RMS-to-dc circuit with a simple S/H circuit eliminates offset errors, which increases accuracy and temperature stability. The circuit in Fig 1 uses a low-cost analog multiplier, IC1; an integrator, IC3A, R5, and C1; and an analog inverter,.....(design idea added 11/05)

Rohde & Schwarz FTZ distortion meter schematic - (circuit added 07/07/07)

Rohde & Schwarz LARU Inductance meter schematic - (circuit added 07/07/07)

RS232 Data Bus Status Indicator - This circuit indicates TXD and RXD activity. The thresholds are set at plus 3 volts and minus 3 volts. (added 12/04) ….(designed by David A. Johnson)

RS232 to TTL converter tests UARTs with a PC - 05/29/08 EDN-Design Ideas: A simple RS-232-to-TTL converter tests UARTs using a PC's serial port for power.....(design idea added 06/07/08)

RS232C Link Monitors Animal Activity - 11/06/97 EDN-Design Ideas: (design idea added 6/06)

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