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Diode Connected Transistors
How to control a Solenoid Valve with Relay and MCU?
I'm having a trouble with my project. I'm making a solenoid valve controller using relay and ATMega8 microcontroller.
The valve is supplied by 220 V AC. I use the relay to connect valve power line. The relay is driven by a ULN2001 IC and the IC get its input from the microcontroller.
I tried the controller without connecting the valve to the relay. It worked well, nothing's wrong.
However when I tried it with the valve connected to the relay, the MCU is reseted every time the relay is switching off to close the valve (the valve is normally closed and the relay is normally opened).
I think it was because of the EMF suddenly collapsed when the relay was swtiched off. So, I put a diode paralel to the relay input to protect the relay. But it still didn't work.
Can anyone help me? Should I use a transistor or opto-coupler instead of ULN IC to drive the relay?
You always need a diode across an inductive load to protect, not the load itself, but the driver output stage. You may have ruined the controller already. If not, you are in luck. What may be happening is a spike on the power supply when the relay switches. You may need more smoothing in the power supply, or to introduce a relay driver (transistor or opto-coupler as you suggest) fed from a separate power supply
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Connected $6.99 Connected |
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Physics of HighSpeed Transistors $332.97 This book examines in detail the new physical principles and technological approaches that make highspeed transistors possible. It includes discussions of maximum drift velocity in semiconductors, hotelectron transistors, and highspeed devices and integrated circuits to provide a comprehensive overview for physicists, engineers, and students who wish to apply this technology to computer and microwave development. Author: Pozhela, Iuras Karlovich/ Pozela, Juras Series Title: Language of Science Binding Type: Hardcover Number of Pages: 355 Publication Date: 1993/12/31 Language: English Dimensions: 9.21 x 6.14 x 0.81 inches |
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Finfets and Other MultiGate Transistors $224.89 This book explains the physics and properties of multigate fieldeffect transistors (MuGFETs), how they are made and how circuit designers can use them to improve the performances of integrated circuits. It covers the emergence of quantum effects due to the reduced size of the devices and describes the evolution of the MOS transistor from classical structures to SOI (silicononinsulator) and then to MuGFETs. Author: Colinge, J. P Series Title: Integrated Circuits and Systems Binding Type: Paperback Number of Pages: 340 Publication Date: 2010/11/25 Language: English Dimensions: 9.21 x 6.14 x 0.74 inches |
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DIODE $12 When these electrical items fail there is little choice but to renew - With this genuine Suzuki par.. |
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Lights on Polymer FieldEffect Transistors $151.35 The book focuses on the electrical properties and photoinduced processes in polymer based fieldeffect transistors PFETs. The photoinduced drain current in the PFETs results from a variety of possible pathways, and is a consequence of a complex charge generation, recombination and transport processes. These processes are observed to be dependent on the gate voltage and demonstrate a coupling between the photoexcitation and transistor features. Considerable increase in drain current upon irradiation, followed by an extremely slow relaxation upon terminating the illumination is the striking feature in poly(3hexylthiophene) based transistor operated under accumulation mode. In depletion mode, the photoresponse becomes strongly dependent on gate voltage. Low dark current in the background, accompanied by large photosensitivity in this mode is exploited to observe memory effect including write, read, store and erase operations. The unique combination of gate bias and light as input parameters for charge transport in polymer transistor and the spatial information of the gate voltage dependent photocarrier generation region are thoroughly investigated using spectroscopic analysis. Author: Dutta, Soumya Binding Type: Paperback Number of Pages: 180 Publication Date: 2011/03/16 Language: English Dimensions: 5.98 x 9.02 x 0.41 inches |
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Systematic Analysis of Bipolar and Mos Transistors $116.88 Systematic Analysis of Bipolar and MOS Transistors is a selfcontained reference that walks you through the logical processes involved in transistor analysis. Linking device and circuit engineering, it shows you how to use device models intelligently, tailor existing models, and develop new ones. Author: Cilingiroglu, Ugur Series Title: Artech House Materials Science Library Binding Type: Hardcover Number of Pages: 248 Publication Date: 1993/12/01 Language: English Dimensions: 9.33 x 6.26 x 0.73 inches |
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The Connected $16.08 No Synopsis Available |
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Understanding Modern Transistors and Diodes $90.77 No Synopsis Available |
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Power Acoustik PTID-8920B In Dash DVD AM-FM Receiver with 7-Inches Flip Out Touchscreen Monitor with USB/SD Input
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DescriptionPlay your favorite DVD's, MP4, DIVX, & XVID movies, or MP3 audio files. We've included a detachable security strip into the face plate that will keep any wanna-be thieves away. Motorized Monitor w/ Angle Memory To eliminate glare and improve visibility, PTID-8920 has 2-way positioning motors that allow for the perfect viewing angle in virturally every vehicle... |
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Power Acoustik PTID-6250B In Dash DVD AM-FM Receiver with 7-Inches Flip Out Touchscreen Monitor with USB/SD Input
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Power Acoustik PTID-6250 In Dash DVD AM-FM Receiver with 7-Inches Flip Out Touchscreen Monitor with USB/SD Input
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DescriptionPOWER ACOUSTIK PTID-6250 6.2" DOUBLE-DIN TOUCHSCREEN TFT/LCD DVD RECEIVER (NO BLUETOOTH(R)) |
DIY Shortwave radio
Why wouldn't this make a good current mirror?
When you build a simple current mirror, you can use two PNP BJT transistors and place equal resistors at the emitters and diode connect (wire collector to base) one of the transistors. My prof said that using NPN transistors and placing a resistor at the collector would not work well. Why is this? It looks like it would do the same thing to me.
The basic idea of a current mirror is to use one transistor to establish the reference current and then mirror that current to bias the other transistors in the circuit. Examine the following circuit
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