-
Categories
-
Platforms
-
Content
-
Enter to Win a Raspberry Pi 4 built into a compact keyboard! We'll be selecting the winner at the end of this month - click here for more information.
is that Brown black red gold?
102 5%
1000 uH
http://www.digikey.com/product-search/en/inductors-coils-chokes/fixed-inductors/196627?k=&pkeyword=&pv19=338&pv3=2&pv16=1&FV=fff40003,fff80013&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25
choose one with low DCR
102 5%
1000 uH
http://www.digikey.com/product-search/en/inductors-coils-chokes/fixed-inductors/196627?k=&pkeyword=&pv19=338&pv3=2&pv16=1&FV=fff40003,fff80013&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25
choose one with low DCR
Last edited:
One of these perhaps?
Supply voltage 24Vdc, signals i/0 24Vdc.
Red coating-warranty ? No, this is not an issue.
As I do not have wiring diagram of this card, I do not want burn down something and wish to get everything running ASAP
Attachments
Last edited:
next question is why did it fail? why was it suspect?
THis choke reduces the current surge charging up the 1000 uF cap to some voltage when switched on. The cap ESR may be lower than the choke DCR of 12 Ohms. thus the current di/dt =V/L where dt is the charge up time.
This is a basic Current spike decoupling choke where the surge current is limited by V/(R_total)
Assuming 20V to a 25V cap worst case, and R_total = 15Ω, I max = 2A for a few milliseconds then expected load should be 200mA for decent load regulation . I would choose a higher current rating choke than 200mA as a guestimate as the choke simply acts as a resistor with low L when saturated.
Even a 12 Ω power resistor might work, but the L reduces pulse ripple current to source supply to triangle waves.
Risk low. 10% tolerance ok if voltage applied is lower, then lower current rating is Ok.
Does this drive small motors? then measure DCR of motors and consider higher. current rating.
THis choke reduces the current surge charging up the 1000 uF cap to some voltage when switched on. The cap ESR may be lower than the choke DCR of 12 Ohms. thus the current di/dt =V/L where dt is the charge up time.
This is a basic Current spike decoupling choke where the surge current is limited by V/(R_total)
Assuming 20V to a 25V cap worst case, and R_total = 15Ω, I max = 2A for a few milliseconds then expected load should be 200mA for decent load regulation . I would choose a higher current rating choke than 200mA as a guestimate as the choke simply acts as a resistor with low L when saturated.
Even a 12 Ω power resistor might work, but the L reduces pulse ripple current to source supply to triangle waves.
Risk low. 10% tolerance ok if voltage applied is lower, then lower current rating is Ok.
Does this drive small motors? then measure DCR of motors and consider higher. current rating.
Last edited:
Good question. Burnt inductance was visible fault when I opened box. Why I opened the box ? Because ultrasonic proximity sensor what was one of the inputs in this card, sometimes malfunctioned.Sometimes not. Sensor seemed to be ok, so my next step was to go further. Actually original one was this:
I had a spare card, but during soldering one leg of inductance brokened.
I had a spare card, but during soldering one leg of inductance brokened.
alec's part seems to be the closest match
To reduce self heating, I would use 500 uH rated for 240mA with DCR of 7Ω which is two of Alec's chokes in parallel . These are like 1/4W resistors which would burn out with 1/2W.
A lower DCR of 3Ω would work but increase dissipation power in 1000uF cap with ripple current.
Often designs like this shunt parallel caps and chokes for redundancy any reliability. Hi Rel designs try to increase the circuit R to limit charge currents to caps.
These days ICL's are used to perform this better, like a Polyfuse but with NTC instead of PTC.
To reduce self heating, I would use 500 uH rated for 240mA with DCR of 7Ω which is two of Alec's chokes in parallel . These are like 1/4W resistors which would burn out with 1/2W.
A lower DCR of 3Ω would work but increase dissipation power in 1000uF cap with ripple current.
Often designs like this shunt parallel caps and chokes for redundancy any reliability. Hi Rel designs try to increase the circuit R to limit charge currents to caps.
These days ICL's are used to perform this better, like a Polyfuse but with NTC instead of PTC.
Last edited:
Thanks, We have figured out exactly the same from Farnell, but looks that bigger mA are rare.
Another thing is color interpretation. I was not sure that first color is brown enough,suspected orange,like here
http://www.electronics2000.co.uk/calc/inductor-code-calculator.php
Another thing is color interpretation. I was not sure that first color is brown enough,suspected orange,like here
http://www.electronics2000.co.uk/calc/inductor-code-calculator.php
I would install a 10Ohm resistor and monitor voltage drop on a DSO scope on slow sweep to decide what is best for DCR.
DCR* mA squared = P rating will be fixed for same size
I recommend http://www.digikey.com/product-detail/en/bel-fuse-inc/0ZRC0015FF1E/507-1329-ND/1560184
in series with 4Ω DCR choke as my guess
DCR* mA squared = P rating will be fixed for same size
I recommend http://www.digikey.com/product-detail/en/bel-fuse-inc/0ZRC0015FF1E/507-1329-ND/1560184
in series with 4Ω DCR choke as my guess
Last edited:
3000uH would result in DCR with 3x DCR , unlikely a good solution.
voltage drop on a 10 or 12 Ω replacement resistor for choke can help you evaluate faulty sensors for excess load current. A PTC could protect the part from overcurrent.
http://www.digikey.com/product-detail/en/bel-fuse-inc/0ZRC0015FF1E/507-1329-ND/1560184
DCR of PTC <10Ω, so 4Ω DCR choke is advised. if used.
http://www.digikey.com/product-detail/en/epcos-tdk/B82144A2105J/495-5614-1-ND/4245953
voltage drop on a 10 or 12 Ω replacement resistor for choke can help you evaluate faulty sensors for excess load current. A PTC could protect the part from overcurrent.
http://www.digikey.com/product-detail/en/bel-fuse-inc/0ZRC0015FF1E/507-1329-ND/1560184
DCR of PTC <10Ω, so 4Ω DCR choke is advised. if used.
http://www.digikey.com/product-detail/en/epcos-tdk/B82144A2105J/495-5614-1-ND/4245953
Last edited:
Experimentation with measuring tools is tricky, because card is installed in tight rack.But we will see.
Anyway, thanks and greetings to you Sunnysky to Canada, I will order some more inductances from Farnell as they dont cost a lot and see what happens. Resistor assortment is acceptable here in local shop.
Now I have something to think.
Anyway, thanks and greetings to you Sunnysky to Canada, I will order some more inductances from Farnell as they dont cost a lot and see what happens. Resistor assortment is acceptable here in local shop.
Now I have something to think.
Similar threads
