UJT-Test:  This testing procedure is for use with a digital multimeter in the OHM's test-range.  The UJT is a solid-state 3-terminal (TO-18 case) emiconductor. 
UJT's are used in pulse/timing, oscillator, sensing, and thyristor triggering circuits. The most common one being probably the 2N2646 from Motorola. (added 2/06)

Ultra-simple Voltage probe:  (circuit / schematic added 6/05)

Understanding CDMA Measurements for Base Stations and their Components:  Aligent Application Note  (added 2/06)

Understanding GSM Transmitter Measurements for Base Transceiver Stations and Their Components:  Aligent App Note  (added 2/06)

Understanding the Fundamental Principles of Vector Network Analysis:  Aligent App Note  (added 2/06)

Use op amp injection for Bode analysis:  09/16/04 EDN Design Ideas  /  (added 1/05)  Bode analysis is an excellent way to measure small-signal stability and loop response in power-supply designs. Bode analysis monitors gain and phase of a control loop. It performs this monitoring by breaking the feedback loop and injecting a signal into the feedback node and then comparing the injected signal with the output signal of the control loop....

Use RS-232C Port to Measure Pressure:  08/01/97 EDN Design Ideas  / (added 6/06)  A simple circuit and accompanying software turn a pressure sensor into an accurate and cheap pressure digitizer that works with any PC's RS-232C COM port. Many manufacturers make micromachined silicon piezoresistive pressure sensors.

Use Your Printer Port as a High Current Ammeter:  07)/06/00 EDN-Design Ideas / (added 6/06) -With a few inexpensive components and INT1Ch, you can turn the printer port of your PC into a high-current ammeter....

Using Vector Modulation Analysis in the Integration, troubleshooting and Design of Digital RF Communications Systems:  Aligent Application Note  (added 2/06)

VCR Tuner Based RF Spectrum Analyzer Schematic:  file open slowly - be patient. (diagram added 05/07)

Versatile Zener Diode Tester:  (electronic Circuit / Schematic added 10/04)

Vital Signs Monitor Consumes Less than 50 µA:  02/02/98 EDN-Design Ideas / (added 6/06)  

Voltage Probe:  (circuit added 9/04)

Voltage Reference improves JFET:  10/26/00 EDN-Design Ideas / (added 05/03) /The common JFET current-source in Figure 1a has average output impedance and depends heavily on the JFET's VP and IDSS variations. These manufacturing variations limit the initial accuracy of the current setpoint that the circuit can obtain with a fixed R1. Most users of JFET current-sources sample VP and IDSS for each lot of JFETs and then select R1 by first solving the quadratic equation ID=IDSS(1–VGS/VP)2 for VGS and then solving.....

Voltmeter Monitors TTL Supplies:  National Semiconductor Application Note   (app note added 2/06)

VU and PPM Audio Metering:  circuits using analog needle meters   (added 5/02)

VU Meter Amplifier:  (electronic schematic / circuit added 4/02)

VU Meter:  5 led VU meter, in PDF format, includes circuit board, text in Finnish   (added 5/02)

VU Stereo Meter:  will indicate the volume level of the audio going to your speakers by lighting up LEDs, based on LM3915 IC   (added 5/02)

Watt-Hour Meter using PIC16C923 and CS5460:  Microchip Application Note Published 16-Oct-00   (app note added 2/06)

Weighting Filter:  Weighting filters are used to determine the "loudness" of sounds, particularly noise. You can very much discuss and criticise sense and nonsense of different weighting filters….(electronic schematic / circuit added 6/07)

Xmas Lights Tester:  (circuit added 9/04)

Zener diode and MM ICs produce true broadband noise:  10/14/00 EDN Design Ideas  / (added 2/06)  A broadband source of white noise can be useful for measuring and testing communications equipment. The source in Figure 1 is simple and produces a large noise signal at its output terminals. The circuit comprises a zener diode and a few amplifying stages. The breakdown occurring in the zener diode is the true source of broadband noise in this design. This process is truly broadband because a substantial amount of noise is....

Zener Diode Tester #2:  (schematic added 8/03)

Zener Diode Tester:  Here is a handy zener diode tester which tests zener diodes with breakdown voltages extending up to 120 volts. The main advantage of this circuit is that it works with a voltage as low as 6V DC and consumes less than 8 mA current. The circuit can be fitted in a 9V battery box. Two-third of the box may be used for four 1.5V batteries and the remaining one-third is sufficient for accommodating this circuit. In this circuit a commonly available transformer with 230V AC ...   (added 10/05)

Zener test circuit serves as dc source:  11/25/04 EDN Design Ideas  / (added 5/05)  This Design Idea describes a versatile test circuit for Zener diodes after yet another misread Zener diode had infiltrated the ranks of 1N4148 diodes assembled on a pc board. As a bonus, the circuit can serve as a moderate-voltage, power-limited adjustable dc source. Although conventional multimeters' resistance ranges typically apply enough voltage to forward-bias most diodes, few can drive a ...