1000 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 :: 07-14-2005 16:36 :: xxargs :: Replies: 3 :: Views: 2008
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 :: 08-22-2008 03:42 :: IanP :: Replies: 3 :: Views: 4473
If you put your free wheeling diode (D) across the inductor (L), the free wheeling current will never go back to the source, it only "turns" in the L-D circuit until vanishing due to dissipation inside D and L.
Analog Circuit Design :: 07-09-2010 18:06 :: monnoliv :: Replies: 14 :: Views: 1006
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 :: 08-14-2009 10:09 :: FvM :: Replies: 1 :: Views: 1266
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 :: 09-29-2011 13:45 :: phatcreators :: Replies: 7 :: Views: 1001
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 :: 02-03-2011 03:38 :: FvM :: Replies: 13 :: Views: 7907
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 :: 02-26-2011 15:46 :: FvM :: Replies: 5 :: Views: 1493
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 15:42 :: FvM :: Replies: 2 :: Views: 1550
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 :: 07-20-2012 07:46 :: FvM :: Replies: 9 :: Views: 8482
Can anyone explain why the designer has not used a free wheel diode on the FET in this circuit?
Even if the FET could withstand the reverse voltage why wouldn't you use a free wheel diode so that the current can flow in both directions through the coil and maximize
Hobby Circuits and Small Projects Problems :: 10-22-2013 21:29 :: boylesg :: Replies: 3 :: Views: 353
The diode is used as a protective element for the MOSFET.
It is called a freewheeling diode which is used to protect the FET from any transient voltages that are generated across it when the FET is involved in switching any inductances.
While normal conduction, this diode remains reverse biased.
When the (...)
Electronic Elementary Questions :: 01-11-2014 13:57 :: Audioguru :: Replies: 5 :: Views: 235
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 :: 07-19-2004 20:07 :: guyaneseboy :: Replies: 23 :: Views: 8731
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 :: 01-26-2007 16:34 :: Mr.Cool :: Replies: 10 :: Views: 1881
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 :: 07-14-2007 11:46 :: barath_87 :: Replies: 3 :: Views: 1253
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 :: 07-25-2007 22:23 :: invent :: Replies: 2 :: Views: 6583
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 :: 08-21-2007 09:06 :: A.Anand Srinivasan :: Replies: 15 :: Views: 4564
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 09:32 :: A.Anand Srinivasan :: Replies: 1 :: Views: 628
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 :: 02-23-2008 01:29 :: joby16 :: Replies: 22 :: Views: 3188
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 :: 09-21-2008 04:56 :: FvM :: Replies: 19 :: Views: 1713
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 :: 10-31-2008 04:18 :: jegandren :: Replies: 11 :: Views: 4937
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 :: 04-23-2009 04:01 :: FvM :: Replies: 5 :: Views: 2650
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 :: 02-11-2010 02:35 :: FvM :: Replies: 8 :: Views: 2374
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 :: 07-30-2010 06:27 :: FvM :: Replies: 11 :: Views: 1439
i went to the SMCUSA website and i cannot find the "SYJ512-5WOZ-M5-F" solonoid valve.
i have found the SYJ500 series datasheet, and i presume that yours is one of that family?....I am not so sure?.....
you just need a bit of stripboard, and a
Electronic Elementary Questions :: 09-03-2010 12:36 :: eem2am :: Replies: 6 :: Views: 1363
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 :: 10-07-2010 07:58 :: pranam77 :: Replies: 4 :: Views: 1379
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 :: 02-04-2011 09:46 :: cocoloco :: Replies: 10 :: Views: 2355
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 13:26 :: yzou_ua :: Replies: 1 :: Views: 361
be sure that reverse and direct voltage produce by motor when you turn on and turn off or changing motor polarity don't effect into source.
maybe if you place zener diode before regulator ,it protect your regulator against over voltage.
so you use free wheeling diode for each transistor (safety).
Electronic Elementary Questions :: 06-07-2011 06:15 :: dv_sa559 :: Replies: 20 :: Views: 1371
You'll need a current sense resistor and a latching overcurrent sense and shut-down circuit. Your circuit is missing a free-wheeling diode for the inductive load, by the way.
Analog Circuit Design :: 06-28-2011 03:34 :: FvM :: Replies: 9 :: Views: 5474
Take wires out of component
First: Preliminary test as atripathi wrote.............
with ohm meter
Second: Test with lamp
How to test MCD version of th
Power Electronics :: 10-09-2011 05:40 :: danishdeshmuk :: Replies: 8 :: Views: 1707
There are two important things missing in your circuit:
- a current limiting means for the the TIP120, e.g a collector resistor
- a free wheeling diode for the coil
The unpleasant point is, that you need to drive the maximum required base current to the 2N3055 (which you calculated as 2.1 A) despite of the actual current gain and burn (...)
Electronic Elementary Questions :: 10-08-2011 18:58 :: FvM :: Replies: 8 :: Views: 1525
free wheeling diode is the simple solution for backEMF..
Microcontrollers :: 12-17-2011 02:19 :: kandhu26 :: Replies: 6 :: Views: 299
In a typical buck/boost converter if you have a free wheeling diode across the MOSFET, can there still be over voltage across the FET? how? would you still need to add a separate clamping diode across it?
Power Electronics :: 12-27-2011 09:55 :: zuq :: Replies: 7 :: Views: 1213
Plausible explanations in my view:
- defective transistor
- you placed a zener diode for the free-wheeling diode
Electronic Elementary Questions :: 01-19-2012 10:00 :: FvM :: Replies: 14 :: Views: 2289
I can only find in Mouser the transistor BU508AF. It does not have a free-wheeling diode! Will it be a problem to put this one? Since these transistor is also suitable to a High voltage NPN power transistor for standard definition CRT display?
---------- Post added at 19:12 ---------- Previous po
Electronic Elementary Questions :: 03-08-2012 12:12 :: brunofunchas :: Replies: 2 :: Views: 1457
try the same circuit ....one some extra precaution that you need to take case here is fan is inductive load so current lags the voltage where as in case of bulb it is resistive load thus voltage and current are in my recommendation is fine tune delay while firing the gate pulse ....also use free wheeling diode across the triac ...
Robotics and Automatics Forum :: 06-21-2012 03:36 :: milind.a.kulkarni :: Replies: 1 :: Views: 418
in that figure i.e.relay....generally relays dealt with high voltages and currents when compared with ic's which consumes current in milli amps,thats why here we have free wheeling diode to protect from back emf's
Electronic Elementary Questions :: 07-17-2012 10:00 :: Electro Builder :: Replies: 3 :: Views: 1104
Fast switching can minimize losses, but the load current can't drop to zero in no time. You need to provide a commutation path, e.g. a free wheeling diode. The fast voltage change at the load can still cause problems like RF interferences. So fast switching isn't enough, the whole circuit has to be designed to support it.
Power Electronics :: 08-21-2012 04:08 :: FvM :: Replies: 25 :: Views: 1283
BTW the reason I used a mechanical relay instead of a FET is because in order to turn on the fan, it needs a surge current. If you slowly apply the 12V, the fan will not turn on. In order to quickly turn on a FET with the output of this device I will have to use another FET driver and it makes things unnecessarily complicated.
Show your DIY :: 10-17-2012 13:21 :: barry :: Replies: 4 :: Views: 1040
I use two same mos diode(G and D connected mosfet which acts like diode) stacked as normal free wheeling diode. The symbol is like the pic1 below because they are insulated mosfet with pwell/dnwell and dnwell/psub junction diodes.
The problem is
1.when the diode is (...)
Analog Circuit Design :: 01-09-2013 04:58 :: nelly1 :: Replies: 0 :: Views: 187
I saw a circuit attached below.
How the zener diode clamping network helps in achieving faster switching and controlling the peak reverse voltage. Also what value of zener diode to be placed there?
I know the purpose of free wheeling diode and seen many circuits using this (...)
Analog Circuit Design :: 06-12-2013 13:24 :: Murugesh_89 :: Replies: 1 :: Views: 277
i didn't understand your capacitor method so i can not say.
but i have built an incredibly efficient battery charger using the "open an inductor" method. yes a free wheeling diode is used to provide a path to send the voltage spike to the charge battery. so i thought i would mention it as one way to get a high voltage in very short (...)
Power Electronics :: 09-11-2013 22:29 :: Mr.Cool :: Replies: 11 :: Views: 968
The diode you made mention is acting as a free wheeling diode (read about it).
You know most microcontroller operate on 5V supply ans since they are operating on 5V, they can not source more than 5V.
Check the datasheet of the MOSFET and get back to me. Most MOSFET need to be triggered by a voltage >8V before they can be (...)
Electronic Elementary Questions :: 10-07-2013 03:03 :: Ogu Reginald :: Replies: 3 :: Views: 300
The voltage calculates as dI/dt*L and is usually higher than the voltage rating of your switch transistor.
You can distinguish two cases:
- you have a free-wheeling diode. In this case you don't care about emf magnitude. Decay time constant L/R might be interesting if fast switching is intended.
- you have a switch transistor with (...)
Electronic Elementary Questions :: 10-18-2013 09:14 :: FvM :: Replies: 11 :: Views: 1017
yes but the relay is in the part of the car that we retrofitters do not have access to......we cannot make changes there.
No, you didn't read the suggestion thorougly. Tunelabguy is suggesting a simple free-wheeling diode. It would be connected in parallel to C6.
Electronic Elementary Questions :: 02-01-2014 08:30 :: FvM :: Replies: 6 :: Views: 254
You should have an idea about the actual motor current, both steady-state and inrush, to determine if the relay is capable to switch it frequently. If not, you don't need to worry about spikes because switching the motor a few times might kill the relay anyway.
The capacitor causes a large inrush current and will make things worse, the 100 ohm e
Power Electronics :: 03-10-2014 18:26 :: FvM :: Replies: 9 :: Views: 381
If the Manufacturer had mentioned the polarity it means there is a diode inside relay preventing inductive behavior of a coil.
Not right for Panasonic TX2-12V and similar types. They have a polarized drive, involving a permanent magnet. You still need free-wheeling diode.
Analog Circuit Design :: 06-16-2014 07:23 :: FvM :: Replies: 6 :: Views: 212
I am trying to make a home made inverter.
I am referring driver side of this schematic
I replaced 2n6277 with two 2n3773 (parallel).
My problem is that the free wheeling diodes I used are getting burned out every time,I removed them and the circuit is working,but I am not using the circuit without fr
Power Electronics :: 08-31-2014 04:48 :: myfaithnka :: Replies: 29 :: Views: 727
Could you please let all of us know the background and describe the purpose of your circuit?
The diode is for free wheeling.
The output from DAC drives a current thru R and generates a voltage.
Another voltage is generated across the 3.3 ohms Rsense by the current (Isink) passing thru the voice coil.
The OP Amp generates a (...)
Analog IC Design and Layout :: 06-13-2007 05:42 :: watermelon :: Replies: 3 :: Views: 2300
actually when we turn off the power across a inductor a voltage spike results due to the di/dt factor and is called inductive kickback.... the free wheel diode is connected across the inductor such that it is reverse biased during normal operation... when supply is turned off the voltage spikes up in the opposite direction due to the direction of r
Analog Circuit Design :: 09-04-2007 07:22 :: A.Anand Srinivasan :: Replies: 3 :: Views: 885