Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com, has 40,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.
We make every effort to link to original material posted by the designer. 
Please let us if you would like us to link to or post your design.

HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


Tester or Instrumentation Circuits, Page 11a
Testers:  #'s     A-B    C     D     E    F-G    H-K    L     M-O    P     Q-R    S    T     U    V-Z

Last Updated on: Wednesday, November 29, 2017 05:38 AM

Circuits Designed by Dave Johnson, P.E. :

  • 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:
Regulator Monitors Its Input Voltage -  09/12/97 EDN-Design Ideas.... EDN is migrating links. This link is not verified.  Google the "title" + EDN for new link.
Remote Control Transmitter -  Although ready-made remote controls are easy to get, with this project we show how to build on at home. Features are impressive, with 6 radio channels and long battery life. Complete with PCB layout. (electronic design added 6/07)

Remote control using telephone -  Here is a tele-remote circuit which enables switching "on" and "off" of appliances through Telephone lines. The circuit described here can be used to switch up to nine appliances (corresponding to the digits1 through 9 of DTMF the Telephone key-pad). The Telephone can be used to switch....(added 5/02)
Remote humidity sensor needs no battery -  4-Apr-02 Issue of EDN  Using ac-line power sources and batteries for remote humidity sensors is undesirable because these sources can be troublesome if you mount them in inaccessible points, such as smokestacks, cold-storage chambers, or darkrooms, where maintenance is difficult and inconvenient. Figure 1 shows a simple way to remove the power source from the humidity-sensor circuit.... [Design Idea by Shyam Tiwari, Sensors Technology Private Ltd, Gwalior, India]
Resistance tester -  Schematic only, no circuit description
Resistance, DC Current, AC Current & Frequency & Period Measurement Errors in Digital Multimeters AN-1389-2 -  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 detectors, level meters, attenuators, dummy loads, signal dividers several circuits on this page…. [Jan-Martin Nøding's site]
RF Isolator Uses Differential Amplifiers -  An RF isolator is a seemingly magic device that allows signals to pass in only one direction. Signals applied to the input port are sent to the test port and signals coming into the test port can only go to the output port. This one-way property is usually accomplished with special non-linear ferrite/magnet structures operating at very high frequencies. Fig. 1 shows an active RF isolator.... [Design by Charles Wenzel]
RF Power Meter -  Many beginners trying out their skill with QRP TX, for the first time have to overcome many problems before they are able to come on the air. On usual complaint is that, every thing is working fine but the signal is not going out. 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. The 8k resistor should be kept close to the out put terminal of the transmitter....(electronic circuit added 9/04)
RF Power Meter for the QRPer -  amateur radio construction projects…. [from Peter Parker's website]
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)
RF signal- and power generators several circuits on this page…. [Jan-Martin Nøding's site]
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.   EDN is migrating links. This link is not verified.  Search the "title" + "EDN" for new link.
RMS Calculations for Energy Meter Applications Using the ADE7756 -  AN-578 Analog Devices Application Notes....[App Note]  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 & 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,.... EDN is migrating links. This link is not verified.  Search the "title" + "EDN" for new link.
Rohde & Schwarz FTZ distortion meter schematic -  (circuit added 07/07/07)
Rohde & Schwarz LARU Inductance meter schematic -  (circuit added 07/07/07)
RS 232 to TTL converter tests UARTs with a PC -  29-May-08 Issue of EDN  A simple RS-232-to-TTL converter tests UARTs using a PC's serial port for power.... [Design Idea by Matthieu Bienvenüe, Malissard, France]
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) …. [Hobby Corner Circuit by Dave Johnson]
RS232C Link Monitors Animal Activity -  11/06/97 EDN-Design Ideas....A common need in biological experimentation is the ability to unobtrusively monitor the activity of small caged animals, such as mice, rats, and rabbits, as they move about their enclosures.  This monitoring must be over long periods and around the clock. The circuit in.... [Design Idea by W Stephen Woodward, University of North Carolina--Chapel Hill]
RS232-to-TTL converter tests UARTs with a PC -  01-Jul-08  EDN Europe  When using a computer for debugging or testing UARTs you often need an RS232-to-TTL adapter. But most of these adapters require an external power-supply adapter to power up the RS-232 transceiver.  This external adapter increases the number of cables on your desk and uses no flowcontrol signals.... [Design Idea by Matthieu Bienvenüe, Malissard, France]
          Testers Previous Q-R's   
Testers:  #'s     A-B    C     D     E    F-G    H-K    L     M-O    P     Q-R    S    T     U    V-Z


HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |    Privacy Policy

Copyright  January, 1998 - November, 2017     David A. Johnson & Associates.  All Rights reserved. 
 Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.