111 Threads found on edaboard.com: Free Wheeling Diode
i am using msr860 as a free wheeling diode across the h- bridge mosfets for both the high and the low but after a short while of operation it fails and goes cocked and then shorted "1 minute ".
it was noted that the -ve portions due to the back emf of the voltage signal had been removed after adding the (...)
Professional Hardware and Electronics Design :: 14.07.2005 22:36 :: xxargs :: Replies: 3 :: Views: 1755
The original term "freewheeling" was related to device(s) that allowed power transmission shafts to rotate "freely" when its speed was greater
than that of the engine to which it was connected. In fact in the cars of the 20's and 30's a selector switch was installed on the steering wheel column allowing the driver to select the mode of oper
Analog Circuit Design :: 22.08.2008 09:42 :: IanP :: Replies: 3 :: Views: 3429
My ARM Board consists of digital their document they had given that"user has to add proper free wheeling diodes across inductive loadsto protect the output transistors against high voltage".
What I have to now to get the output?what are freewheeling diodes?
Analog Circuit Design :: 29.06.2010 07:24 :: Shreehari :: Replies: 14 :: Views: 780
According to figure 1, when we want to run single phase motor, we use free wheel diode along to motor. but according to figure 2, if we want to use 3 phase motor, is it necessary to use FWD? if so, where should we place it? ( it's not possible to place it along 2 phase of motor)
Analog Circuit Design :: 04.08.2011 08:41 :: ata90 :: Replies: 15 :: Views: 1305
You typically don't need free-wheeling diodes, but you should use synchronous free-wheeling in a full bridge if ever possible. Standard PWM schemes are using it.
Power Electronics :: 14.08.2009 16:09 :: FvM :: Replies: 1 :: Views: 975
Negative voltages as such won't affect the transistor, but with an inductive load, the negative voltage can be quite high and possibly exceed the transistor's voltage rating. It's a simple free-wheeling diode.
Electronic Elementary Questions :: 03.02.2011 09:38 :: FvM :: Replies: 13 :: Views: 5077
Most people use a simple free-wheeling diode. The voltage rating has to be higher than supply voltage, but isn't critical. You can use 1N4148 or similar SMD devices. If a very fast relay release is intended, you can connect all free wheeling diodes to the highest available supply voltage, if (...)
Analog Circuit Design :: 26.02.2011 21:46 :: FvM :: Replies: 5 :: Views: 1150
To reduce the relay voltage, you have to connect zener diode (3V9) or simply a resistor in series with the relay coil. The free wheeling diode (1N4007) should be connected as usual.
A zener diode parallel to the coil would overload the diode as well as the driving switch and possibly (...)
Robotics and Automatics Forum :: 05.05.2011 21:42 :: FvM :: Replies: 2 :: Views: 1126
Actually , the current developed in relay inductance cannot be disrupted when the collector is OFF.The dV/dT goes very high and breaks down the Vce of the drive transistor .If you return this to supply as a freewheeling diode ,it is OK Alternatively , you need to protect the driver collector and later coil flashover shorting .If you can (...)
Analog Circuit Design :: 28.08.2011 18:34 :: vimalkhanna :: Replies: 13 :: Views: 875
How to test this IGBT module BSM 50 GD120DN2E3226 having 6 IGBTs with free wheeling diodes connected across all of the six IGBTs ?
Power Electronics :: 29.09.2011 19:45 :: phatcreators :: Replies: 7 :: Views: 681
There's no overcurrent protection (e.g. to handle motor short or stall) in your circuit and it won't be easy to achieve.
The free wheeling diode is essential, the TVS diodes are not neccessarily required and may possibly affect the cicuit performance.
Vds overvoltage is also limited by the FET avalanche breakdown (...)
Analog Circuit Design :: 20.07.2012 13:46 :: FvM :: Replies: 9 :: Views: 1670
i have also experienced this problem, but i think u need to have a free-wheeling diode across the coil of the relay. :idea:
i am quite sure this will work. The pic resets as the coil, when s/w on and off causes a back emf , which disturbs the gnd. u dont need a good pcb or a 10k with cap on th eMCLR pin, i normallyu pull it (...)
Microcontrollers :: 22.04.2004 16:19 :: sam_manchali :: Replies: 14 :: Views: 8118
I still prefer the flyback over the Push-Pull
a)The 200W limit (I have done a 500W with a few tricks) is within the reach of modern MOSFETS current wise when operating on 24VDC. (I won't go to 12V)
b) The flyback transformer construction is more simple. When operating at fairly high frequencies when you need only a few turn's on the
Analog Circuit Design :: 18.06.2004 03:55 :: E-design :: Replies: 10 :: Views: 3208
Use a seperate supply to drive the relay coil and use an optocoupler to drive the BJT. Do not forget the free wheeling diode to supress inductive kickback ( across the BJT collector to the relay positive supply as previously mentioned). The return ground(s) for the logic circuit and relay
should be a single (star) connection at the (...)
Professional Hardware and Electronics Design :: 20.07.2004 02:07 :: guyaneseboy :: Replies: 23 :: Views: 6772
The motor connected as load is inductive. Make sure that the o/p darlington's have built-in free- wheeling diodes. TIP142/147 have it. Don't remember about TIP122/127.
If they don't then connect one across each of the four o/p devices.
Also you need to connect a resistor between base and emitter of all the four o/p devices. The value of (...)
Electronic Elementary Questions :: 21.07.2004 15:35 :: bimbla :: Replies: 17 :: Views: 7912
A proper freewheling diode has solved my problem. Without diode, motor starts up only at high duty cycle, with fwd it runs normal.
Robotics and Automatics Forum :: 18.10.2004 21:11 :: seyyah :: Replies: 9 :: Views: 2085
I am using a seperate electronic speed controller with the motor like the one shown in figure.
Any ideas how to use it ?
I also need to build a circuit to control the speeds to desirable values.
hmm - see 3 big conducts to motor - in real world 3 phase AC-motors with
outside ajustable AC-converter???
this is n
Hobby Circuits and Small Projects Problems :: 30.04.2005 14:59 :: xxargs :: Replies: 15 :: Views: 5110
Hi all, i need to drive drive this dc motor. i build my H-bridge using high rated current and voltage Mosfets(50V 50A max) and control it using a PIC uC. I even include the free-wheeling diode accross the Mosfets and interface optoisolator between the uC and the H-bridge. But when i increase the load of motor suddenly, it just damage my (...)
Hobby Circuits and Small Projects Problems :: 05.03.2006 18:26 :: wakaka :: Replies: 15 :: Views: 1925
Influence of Gate Resistor
With external gate resistor connection, designers can control the IGBT gate signal flow, and have an option to slow down the device commutation; therefore reducing the amount of Electro-Magnetic Interference (EMI) compared to intelligent power module (IPM) solution.
Series gate resistor is typically used f
Electronic Elementary Questions :: 15.03.2006 11:42 :: IanP :: Replies: 3 :: Views: 2563
this is a problem of emi /emc. Chekc the following and you may have a solution:
1. is your crystal properly grounded? if not, make it horizontal and ground the body.
2. have you implemented the MCLR circuit as recommended in the datasheet. If your controller supports internal MCLR, use internal. it is more stable in EMI problems.
3. put a free w
Microcontrollers :: 12.07.2006 23:41 :: pawanbahl :: Replies: 17 :: Views: 1783
mosfets are a better choice because they come with the free-wheeling diode for free. the BJT you must add this seperately. also, it is simple to drive MOSFET.
i see on your schematic B_HS is labeled, but since i don't see an off-page connector i wonder if it is connected to your microcontroller?
make sure you're (...)
Hobby Circuits and Small Projects Problems :: 26.01.2007 22:34 :: Mr.Cool :: Replies: 10 :: Views: 1696
This is a self oscillating buck converter.
R4 helps keep Q7 off when it is supposed to be off and is essential.
R1,2,3 turn Q8 on which turns Q7 on which puts power thru to the output, R5 limits the base current in Q7.
When the ouput volts get high enough DZ1 conducts turning on Q9 and charging C4, Q8,7 turn off and remain off while C4 charges
Analog Circuit Design :: 09.03.2011 03:21 :: Orson Cart :: Replies: 16 :: Views: 964
use a MOSFET (give your control input gate that will allow signal to flow from drain to source(nmos))and be carefull if you are going to drive a relay you will have to put a free wheeling diode....You can refer to any website or books on electronic devices boyelstead or sedhra & smith
Hobby Circuits and Small Projects Problems :: 14.07.2007 17:46 :: barath_87 :: Replies: 3 :: Views: 1071
Inductive kick is very common in motors because of the coils in them. When there is a change in the current of the coils (i.e. the motor being switched off), a high voltage spike will develope.
A free wheeling diode is used to provide an alternate path for the this high current to flow and prevent damage to the switch.
The links below (...)
Analog Circuit Design :: 26.07.2007 04:23 :: invent :: Replies: 2 :: Views: 2880
connect a diode across the relay in reverse bias under normal operation,.... this will take care of the protection.... this diode is called free wheeling diode....
Electronic Elementary Questions :: 21.08.2007 15:06 :: A.Anand Srinivasan :: Replies: 15 :: Views: 4034
try using a current diode... which is nothing but a diode connected MOS... dont forget the free-wheeling diode....
Analog Circuit Design :: 10.10.2007 15:32 :: A.Anand Srinivasan :: Replies: 1 :: Views: 476
you'll also need a free-wheeling diode in parallel with your motor or you'll blow up your switching device.
oops! forgot to mention this ... ;P
Hobby Circuits and Small Projects Problems :: 23.10.2007 01:02 :: Mr.Cool :: Replies: 11 :: Views: 4643
Use a driver/ Transistor for driving the relay from 89S52. (Eg: ULN2803 , IRF7313 etc)
Connect the Relay coil to the output(collector/ Drain) of the driver and the 12V supply.
Also attach a free wheeling diode for relay protection.
Microcontrollers :: 23.02.2008 07:29 :: joby16 :: Replies: 22 :: Views: 2751
Logic Level MOS usually need around 5 V to conduct well so I have some suggestion:
1) check the voltage output of the parallel port. If the pc is quite old you can find TTL level or 3.5 V a logic high. This voltage could not be enough. If you have CMOS level (most probable) you'll find around 5V. By the way with UL2003 you don't have this probl
Hobby Circuits and Small Projects Problems :: 10.06.2008 21:25 :: trapoe :: Replies: 43 :: Views: 8833
If no current feedback is intended, a logic-level MOSFET and a free-wheeling diode at the solenoid would be sufficient.
Microcontrollers :: 07.08.2008 13:27 :: FvM :: Replies: 19 :: Views: 6110
The circuit is missing the buck-converter free-wheeling diode. This must not necessary cause the spikes but is bad anyway, because all output current loads the transformer.
Analog Circuit Design :: 21.09.2008 10:56 :: FvM :: Replies: 19 :: Views: 1483
A freewheeling diode must be present to suppress negative output voltages when opening the switch. Furthermore, without a low-side switch, there must be at least a resistive load to charge the bootstrap capacitor.
I also don't see the purpose of the diode-inductor series circuit.
I have attached the the circuit w
Analog Circuit Design :: 31.10.2008 09:18 :: jegandren :: Replies: 11 :: Views: 3597
I'm not sure if I understand you.
You want to drive a coil with 110 VDC? And use a reed relay to control 110 VDC?
I would think your relay is dead due to "inductive kickback".
When you energize the coil with DC it makes a field.
Then when you open the relay the field collapses. That collapsing field makes
a huge voltage/current. You need a d
Electronic Elementary Questions :: 08.01.2009 23:46 :: treitmey :: Replies: 2 :: Views: 1143
Without a freewheeling diode between the Q3/L1 junction and ground, L1 is merely a resistor. Suggest adding a diode with cath to L1. Looks like some capacitance is needed on the output too.
Analog Circuit Design :: 07.08.2009 02:35 :: Tralfaz :: Replies: 18 :: Views: 3302
In principle, it's a buck converter of course. The alternative is in using the motor inductance as energy storage (connecting a fast free-wheeling diode and a PWM switch only) or use an external inductor and possibly a filter capacitor, supplying DC to the motor. I guess, the first variant is used in the manufacturer design, but it should be (...)
Hobby Circuits and Small Projects Problems :: 23.04.2009 10:01 :: FvM :: Replies: 5 :: Views: 2264
Here are some problems in your circuit.
There is no crystal.
There is no reset circuit for microcontroller
EA pin is floating. Connect it to +5V
No power connected to microcontroller
Pin 2 of DB9 should go to Tx and pin 3 should go to Rx through MAX232.
Base resistors of transistors are too small. Use atleast 1k.
There are no free-wheeling
Microcontrollers :: 31.08.2009 23:32 :: CMOS :: Replies: 15 :: Views: 5022
You´ll need to add snubbers or free wheel diodes to the relay´s coils. I don´t think the relays can damage the ULN2803 driver but they can cause erratic behaviour of the mcu.
Microcontrollers :: 06.09.2009 06:26 :: pauloynski :: Replies: 8 :: Views: 1034
I wish to control the speed (close-loop control with speed feedback) of a dc motor via PWM field winding voltage control (see attached figure). Do I need any diode in the circuit? Is the voltage seen at the terminals of field winding "ripple free"? Is the current flowing through the field winding "ripple free"?
Electronic Elementary Questions :: 11.11.2009 15:13 :: powersys :: Replies: 3 :: Views: 1369
I don't think, that another SOT-23 MOSFET will work better without connecting a free-wheeling diode at the inductor.
Generally, all recent MOSFETs are internally protected against inductive overvoltages by a zener diode. If the
transistor fails with inductive load, you should expect, that the stored energy respective (...)
Analog Circuit Design :: 11.02.2010 08:35 :: FvM :: Replies: 8 :: Views: 1972
Just use a 63ADC Isolator which is a electrical part having the Current capacity and braking capacity specified. MCBs may be costly for you but are more better than Isolator. I recomend Legrand.
You may use a 70A free wheeling diode for extra protection but it i
Power Electronics :: 18.03.2010 17:52 :: BADFLOPPY :: Replies: 7 :: Views: 557
I have a flyback configuration as a part of a more complicated low power design.
in this design I must disconnect the secondary winding from output capacitor
using a switch or a device funktioning as a switch.
Since this switch must be placed between the secondary winding(which has floating voltage levels)
and output capacitor(which is b
Power Electronics :: 18.04.2010 00:55 :: daniel_p :: Replies: 3 :: Views: 1012
regarding my question about turning the IGBT on, i found out that there is that MOSFET/IGBT driver that does the job but i'm not sure how it is used yet, i'v read it can be turned on with a logic level signal.
It's not that simple. High power MOSFETS and IGBT can be turned ON or OFF with logic level signal but these signals must c
Electronic Elementary Questions :: 18.06.2010 00:58 :: fcfusion :: Replies: 3 :: Views: 1316
The above suggestions are good. Up to medium PWM frequencies (several 10 kHz), BC5xx and 22 ohm gate resistor would be sufficient, I think. The missing free-wheeling diode is the key point, assuming the load is actually inductive, as the "L1" designator says.
Hobby Circuits and Small Projects Problems :: 30.07.2010 12:27 :: FvM :: Replies: 11 :: Views: 1210
We have a normally-closed solonoid valve which we are using to hold open a pipe in a domestic water supply pipe.
we are holding this solonoid valve on by PWM'ing a MOSFET in series with the solonoid valve's coil. (obviously we also have a free-wheeling diode)
The supply voltage to the solonoid valve is 36VDC.
Power Electronics :: 03.09.2010 16:37 :: eem2am :: Replies: 9 :: Views: 1415
I mainly wanted to remind to a category of products, that seems to fit your requirements, not suggest a particular solution. There are more of
It's true, that a free-wheeling diode is the most effective way to handle the stored energy of a solenoid coil. A solid state relays wit
Electronic Elementary Questions :: 03.09.2010 21:20 :: FvM :: Replies: 6 :: Views: 803
The IC is an integration of an array of darligton transistors at each channel. Pin 1 of the IC is equivalent to the base of an NPN transistor and PIN 16 is the collector of the same transistor whose emitter is grounded. A free wheeling diode is internally connected from every output pin to a common pin 10 in your case. Below given is the (...)
Hobby Circuits and Small Projects Problems :: 07.10.2010 13:58 :: pranam77 :: Replies: 4 :: Views: 1115
The RS232 interface at the PIC side is mysterious. I would expect dedicated RX and TX pins (hardware UART) connected to the MAX232.
You also managed to confuse simple things as a transistor relay driver. Unless you have unsaid special intentions, you should go for the text books standard common emitter configuration with current limiting base r
Microcontrollers :: 19.02.2011 11:20 :: FvM :: Replies: 56 :: Views: 2008
it's a common problem,
first use free wheeling diode on 2003(pin9,same V+ as relay),and dont forget to declare all inused port
(i put all inused port to output and low)
and cap .1 near V+ of pic
Microcontrollers :: 04.02.2011 15:46 :: cocoloco :: Replies: 7 :: Views: 1251
I'm trying to add a snubber to this igbt and found useful formulas in a thesis.
For Cs = ( Io * Tfi) / (2 * Vd )
Io : average current ( rated current i guess ? )
Tfi : current fall time transistor ( in FS50 datasheet , same meaning as " fall time in
Power Electronics :: 05.03.2011 17:03 :: jmx66 :: Replies: 11 :: Views: 1288
I have a IGBT mudule(attached), need a heatsink to work. It has specifications as:
"0.88C/W IGBT thermal resistance per 1/6 module as well as 1.25C/W free-wheeling diode thermal resistance per 1/6 module" - pp.4.
So, the thermal resistance should be calculated as: 0.88*6+1.25*6=12.87 °C/watt ?? Is that right??
Power Electronics :: 04.04.2011 19:26 :: yzou_ua :: Replies: 1 :: Views: 242