Source of Datasheets for Transformers

Thread Starter

RAMBO999

Joined Feb 26, 2018
256
Hello all

Does anyone know where I can find a comprehensive source of datasheets for these small transformers that
you find typically on power boards. See the attached image. I am looking for power ratings, coil configs etc.
I have a few that I have removed from scrap boards and I just want to play with them and get to know them.

Cheers
 

Attachments

MaxHeadRoom

Joined Jul 18, 2013
23,362
You may, or may not have luck with actual part No's. but you can get an idea of va size by comparing to those sold on sites such as DigiKey etc.
The voltage should be ascertainable by powering the primary, many come with dual primaries and secondaries so you would have to do a resistance check of all windings to find out the high and low primary voltage connections.
Just ensure they are mains transformers, some could be from SMPS supplies, and will not operate on mains supply.
Max.
 

ronsimpson

Joined Oct 7, 2019
1,317
Coilcraft.com has many transformer for certain jobs. Input voltage/output voltage/current/ type of PWM example circuits, etc.
You will not find the part you have in your hand.
 

sagor

Joined Mar 10, 2019
469
Many, if not most, of those transformers are custom made for the board in question, based on the manufacturer's design. Unless you know the manufacturer, it is very hard to find out specifics. If the transformer is from a switching power supply, even more custom and even more hard to find any information on them.
If the transformer has a name brand on it, you can usually contact the transformer manufacturer and ask for details. In some cases, they will not give details due to the customer's proprietary build of the transformer. In other cases, they will respond with details.
Most of those "mystery" transformers have numbers on them that are specific to the build, not specific to the transformer characteristics. That is, you cannot read the input or output voltages from the part numbers, nor look them up in some master reference.
 

Thread Starter

RAMBO999

Joined Feb 26, 2018
256
You may, or may not have luck with actual part No's. but you can get an idea of va size by comparing to those sold on sites such as DigiKey etc.
The voltage should be ascertainable by powering the primary, many come with dual primaries and secondaries so you would have to do a resistance check of all windings to find out the high and low primary voltage connections.
Just ensure they are mains transformers, some could be from SMPS supplies, and will not operate on mains supply.
Max.
I have put a meter across the one in the picture and from a connectivity perspective this is what I have. The P and S assignment are an assumption btw. Pins 7 to 10 look like they could be dual primary as you mention. Same for the secondary 1 to 3 and 4 to 6. The sort of questions I have are what would happen if I bridged 8 and 9. The resistance between 7 / 9 and 8 / 10 are both the same resistance which suggests that bridging 8 and 9 might double the number of primary coils which could allow this transformer to be used as either a step up or step down depending on how the primary is connected up. The same is true on the secondary side. Pins 1 / 2 / 3 have the same resistance as pins 4 / 5 / 6. How does this sound? Reasonable? Before I start hooking it up to power.
 

Attachments

Thread Starter

RAMBO999

Joined Feb 26, 2018
256
Many, if not most, of those transformers are custom made for the board in question, based on the manufacturer's design. Unless you know the manufacturer, it is very hard to find out specifics. If the transformer is from a switching power supply, even more custom and even more hard to find any information on them.
If the transformer has a name brand on it, you can usually contact the transformer manufacturer and ask for details. In some cases, they will not give details due to the customer's proprietary build of the transformer. In other cases, they will respond with details.
Most of those "mystery" transformers have numbers on them that are specific to the build, not specific to the transformer characteristics. That is, you cannot read the input or output voltages from the part numbers, nor look them up in some master reference.
Thanks. My attempts to find this information so far tend to confirm what you write.
 

MaxHeadRoom

Joined Jul 18, 2013
23,362
A guess 7&8 and 9&10 connected for parallel operation.
connect power to 9&10 and 8, leave 7 unconnected measure from 8 to 7 and the result should be ~0v, if high voltage then connect 8&9 and 10, measure from 10 to 7, should be 0v, or close.
Once you arrive a close to zero, the second open pair can be connected .
This is for a LV primary connection only the higher voltage primary would be both in series.
Max.
 
Last edited:

Thread Starter

RAMBO999

Joined Feb 26, 2018
256
A guess 7&8 and 9&10 connected for parallel operation.
connect power to 9&10 and 8, leave 7 unconnected measure from 8 to 7 and the result should be ~0v, if high voltage then connect 8&9 and 10, measure from 10 to 7, should be 0v, or close.
Once you arrive a close to zero, the second open pair can be connected .
This is for a LV primary connection only the higher voltage primary would be both in series.
Max.
Thanks. I will give it a shot.
 
Top