Todays deals on Voltage Current?

1nA-10A,1mkV-10V 0.02% Calibrator programable Voltage&Current P321 an-g of FLUKE $2,930.00

Advantest R6161 DC Voltage / Current Generator $3,830.00

1nA-100mA,10mkV-1000V,0.02% Calibrator programable Voltage&Current P320 an-g. GR $2,800.00

ADVANTEST R6243 DC VOLTAGE CURRENT SOURCE/MONITOR NEW. $2,888.00

ADVANTEST R6244 DC VOLTAGE CURRENT SOURCE/MONITOR NEW. $2,888.00

ADVANTEST R6243 DC VOLTAGE CURRENT SOURCE/MONITOR NEW. $2,888.00

ADVANTEST R6161 Voltage Current Source + Opt 01 1200 V $2,995.00

SEL-387E Current Differential and Voltage Relay $2,500.00

*NEW* Allen Bradley 1771-IL /D 1771-1L PLC-5 Analog Current/Voltage Input Module $1,868.95

Keithley 228A Prog Voltage Current Sourc 100V/10A $1,495.00

Sorensen DCS 40-25E; DCS 40-25E Voltage 0-40 Current 0-25 $1,195.00

HIOKI VOLTAGE OUTPUT CURRENT CLAMP ON PROBES 9660 QTY. 3 and 9694 QTY. 3 W/ EXTS $1,199.99

KEITHLEY 228A Voltage & Current Source $998.00

Square D CVMT Current/Voltage Module Transient $1,050.00

Sorensen DCS 40-25E; DCS 40-25E Voltage 0-40 Current 0-25 $1,000.00

TELOG 836i LINECORDER VOLTAGE AND CURRENT RECORDER $999.00

EDC Electronic Development Corporation CR103 voltage and current calibrator $899.99

RELIANCE PRINTED CIRCUIT CURRENT VOLTAGE TRANSDUCTOR 51831-6 $850.00

Keithley 706 Scanner +3x 7053 High Current 3x 7059 Low Voltage Plugin Cards $852.99

KEITHLEY MODEL 228A VOLTAGE / CURRENT SOURCE $775.99

*NEW* Allen Bradley 1756-IF6I /A ControlLogix Current/Voltage Input Module $779.18

EDC CR103 DC CURRENT & VOLTAGE STANDARD CALIBRATOR $699.00

NEW RELIANCE ELECTIC 0-51831-3 CURRENT VOLTAGE CARD 0518313 $650.00

RONAN ENGINEERING COMPANY MODEL X85 METER CALIBRATOR for CURRENT, VOLTAGE, OHMS, $600.00

*NEW SEALED* Allen Bradley 1769-IF4 /A CompactLogix 4-Ch Current/Voltage Input $565.00

Xanterx Sorensen Dual DC Power Supply Variable Voltage 0-60V Current Bench Lab $499.99

Reliance 0-51831-1 PC Board Current Voltage CVTB $510.00

RELIANCE 0-51831-3 CURRENT VOLTAGE CARD ***RFB*** $499.00

Reliance CVTH Card 0-51831-7 Current Voltage $499.99

(5) Transducers : current, voltage, frequency, (2) power $500.00

MCC DAQ CIO-DAC02 VOLTAGE/CURRENT OUTPUT PCB CBEQC-1 94V-0 15-06 194350A-01 $499.00

ADVANTEST R6142 Programmable DC Voltage Current Generator Solar Power $509.99

LOT OF 4 PHOENIX CURRENT MONITOR VOLTAGE RELAY EMD-FL-C-10 USED $475.00

PROVA-2000 True RMS Digital Clamp Meter DC/AC 2000A Current Voltage Resistance Ω $399.00

MARTEL IVC-222 HAND HELD VOLTAGE CURRENT CALIBRATOR $400.00

AFLEX 3002 Flexible AC Current Clamp w/ Voltage Measure $375.00

*NEW FS* ALLEN BRADLEY 1769 IF4 /B 4 CHNL ANALOG CURRENT / VOLTAGE INPUT MODULE $399.00

DIY tool High Precision Voltage Current Calibrator H715 $389.90

AFLEX 3002 Flexible AC Current Clamp w/ Voltage Measure $352.50

AFLEX 3002 Flexible AC Current Clamp w/ Voltage Measure $352.50

Omega Engineering Om104 Thermocouple, Voltage, & Current Scanner $380.00

AEMC L562 Simple Logger II (TRMS Voltage & Current) $367.08

200x BU508A High Voltage Current NPN Transistor NEW m $367.00

MASTECH MS7221 Volt/mA Voltage Current Calibrator Meter $365.00

Martel IVC-222HPII Precision Voltage/Current Calibrator w/Case, Leads & Guide $350.00

RELIANCE 0-51831-2 PC BOARD CURRENT VOLTAGE **XLNT** $350.00

Transient Voltage Surge Suppressor Current Technology $350.00

UT712 PROCESS CALIBRATOR VOLTAGE CURRENT SOURCE DMM NEW $339.99

◥◣Facts Engineering 405-8ADC-1 Analog Input Voltage Current 8 Channel◢◤ $329.00

UT712 PROCESS CALIBRATOR VOLTAGE CURRENT SOURCE DMM NEW $339.99

UT712 Voltage Current Soure Process Calibrator USB $339.00

UNI-T UT712 Process Calibrator Volt mA Voltage Current $279.00

MASTECH MS7221 Volt/mA Voltage Current Calibrator Meter $299.99

MASTECH MS7221 Volt/mA Voltage Current Calibrator Meter $299.99

MS7221 Volt/mA Voltage Current Calibrator Meter $299.99

MS7221 Volt/mA Voltage Current Calibrator Meter $299.99

Extech DL160 Dual Input True RMS AC Voltage/Current Dat $299.99

Martel IVC-222 Hand Held Voltage/ Current Calibrator KK10 $299.98

REED VC04 Voltage/Current Simulator $296.65

UNI-T UT712 Voltage Current / Process Calibrator Loop/Measure/Source V/mA $290.00

CC-421 V/A Voltage/Current Calibrator Power Process Calibrating Device LUTRON $288.00

*NEW* Siemens 6ES7334-0CE01-0AA0 6ES7 334-0CE01-0AA0 SM 334 Current/Voltage I/O $284.28

Voltage Current V/mA Loop Process Calibrator Sourcing Simulation 0-20mA 24V 707 $265.00

ROCHESTER INSTRUMENT SYSTEMS RIS CT-1214 NEW VOLTAGE/CURRENT ALARM CT1214 $250.00

Extech 412355A Current and Voltage Calibrator/Meter $259.99

Reliance CVTC PC Board Current Voltage 0-51831-2 * $243.36

New Kyoritsu Voltage Current Resistance Digital Clamp Meters 2055 $250.00

New Kyoritsu Voltage Current Digital Clamp Meters / True RMS Tester 2046R $250.00

Reliance CVTC 0-51831-2 Current Voltage Board ~60 DAY WARRANTY~ $250.00

New Kyoritsu Voltage Current Digital Clamp Meters / True RMS Tester 2046R $250.00

NEW Extech DL150 True RMS AC Voltage/Current Datalogger – Authorized Distributor $249.99

Extech DL150 True RMS AC Voltage/Current Datalogger $249.99

NEW Digital Process Calibrator Volt/mA/Voltage/Current Tester Measurement VA700 $249.90

Pasar CT-10 Low voltage current tracer kit circuit tracer nice condition $229.00

Atten TPR3005T single constant voltage constant current DC power supply $159.00

CC-421 V/A Voltage/Current Calibrator Power Process Calibrating Device LUTRON $210.00

Siemens 6ES7334-0CE01-0AA0 6ES7 334-0CE01-0AA0 SM 334 Current/Voltage I/O QTY $231.90

100p Original L200C Adjustable Voltage & Current Regulator IC NEW (&29) $228.00

DT-5302 Small Resistance 4-wire Kelvin Ohm Capacitance Voltage Current Amp Meter $199.95

100,High Voltage Current NPN Transistor BU508A BU508 m $212.00

100,High Voltage Current NPN Transistor BU508A BU508 m $212.00

100pcs, BU508A High Voltage Current NPN Transistor $211.00

New AC DC Output Input/Output Voltage/Current Signal LCD Loop Calibrator $168.00

Reliance Electric Current Voltage Board 0-51831-1 CVTB $200.00

Vintage Analog Tube Meter Movements Plate Voltage Current Grid Voltage $189.00

HP Agilent 44727C 4 Channel Voltage/Current DAC $200.00

AC DC Output Input/Output Voltage/Current Signal LCD Display Loop Calibrator $199.99

GE Versamax Analog input module. 4 channel Voltage/Current IC200ALG230A NIB $185.00

RIS SC-8302 HI DENSITY VOLTAGE/CURRENT TRANSMITTER- NEW $189.99

LCD Display Voltage Current Signal Loop Electronic Calibrator Tool $168.00

0-22mA Current Voltage Source Frequency Process Calibrator & Multimeter 782 $195.00

Digital Bench Voltage Current Hz Power & Power Factor Meter Tester Alert PF9901 $125.00

Reliance 0-51831 PC Board Current Voltage CVTB $180.00

Fluke T5-H5-1AC Kit Voltage & Current Tester , Holster $182.95

Loop Calibrator for Input/Output Voltage/Current Signal/working voltage measure $188.00

Input/Output Voltage/Current Signal Loop Electronic Calibrator with LCD Display $188.00

Fluke 317 True RMS AC Current Voltage Clamp Meter $169.99

DC Voltage 0-10V Current 0-22mA Process Loop Calibrator Multimeter 705 $184.00

Reliance 0-51831-3 PC Board Current Voltage CVTD $169.00

Extech DL150 Datalogger, True RMS AC Voltage/Current $180.95

Voltage Current Questions

Constant current / constant voltage – Low voltage LEDs and their driving circuits

As LED technology develops and new solutions appear on the market nearly every week, it is getting more difficult to find out which solution is the best for your applications and most importantly, what features you have to pay attention to during purchase. In my previous article at LEDcentre.uk.com about general features of LED transformers I already mentioned that LEDs require special transformers features.

 

LEDs are highly sensitive to changes both in voltage and current, so if you are dealing with low voltage LED lights, wire-wound, stabilized transformers are the safe solution. As mentioned in the article, the majority of household LED lights operating at low voltage require constant voltage drivers for their operation. However, recently, with the increase of high power LED technology, constant current circuit solutions are becoming more frequent. Below, I will give a short description of how these circuits work, and why it is necessary to pay attention to details at the purchase of the driver for these applications.

 

Three components matter in the operation of LED lights: voltage, current and heat. LEDs are highly sensitive to a change in all three of these, so their regulation is very important for gaining a long lifespan. Current is often looked at as an exponential function of voltage, therefore even a small volume of change in voltage can result in a large change in the current. This is exactly why the majority of the LED lights need stabilized constant voltage power supply. However, current load can also increase with the increase of heat. To avoid overloading, LEDs are driven from low voltage DC via a current limiting resistor or constant current regulators. Another additional solution is the cooling of the LEDs with heat sinks. Not all LEDs are attached to heat sinks though, which is why the limitation on the hours of application is so important. If LEDs are operated longer than they are supposed to, they overheat, increasing the current (even if within the range limited by the resistor), and lose some of their lifespan.

 

Constant current circuits are especially safe for high power LED lights, as they are suitable for 24/7 operation. If the LED light is manufactured with constant current circuit, the current is fixed by the stabilized transformer, and it does not generate further heat within the LED light. By less heat generation, the LED gains a longer lifespan. Also, constant current source keeps the LEDs brightness constant. These constant current lights are, however, not suitable for operation with 12V batteries, since batteries are constant voltage power supplies. .

 

There are obviously advantages of both circuits, and as usual we could conclude that details matter. Never use a light requiring constant current with batteries or constant voltage power supplies. Always check this feature of your light, and buy the necessary transformer. And if you would like to know more about LED lights, check out the rest of my articles or contact us at LEDcentre.uk.com.

 

About the Author

Anita Samuelis works at LEDcentre.uk.com, a company that offers a wide range of low and main voltage, eco-friendly, energy efficient and cool running LED lights, like LED GU10, LED MR11, LED MR16, G4 LEDs and B22/E27 light bulbs and flexible water proof LED strip lights ideal for homes, offices, shops, boats or caravans. For more information visit their site at http://www.ledcentre.uk.com

 

Voltage Current Videos

Voltage and Current, Part 1

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