Hi,
in the past (i.e. in my youth) I've successfully wound dozens of transformers, both power and output transformers, as well as chokes. I did it the, say, German way, using flanged bobbins and serrated insulation foils. Both are (were?) very common here and make winding a relatively easy-peasy job.
Now I've harvested quite a number of power transformers from cheesy transistorized Hammond organs. Unfortunately, most of them feature 115 Vac primary windings, hence aren't much of use for me in their present state. So I'm about to rewind (some of) them. Even more unfortunately they weren't wound on flanged bobbins, just rectangular tubes are there.
That makes me scratching my head now. What precautions do I need to do to prevent the magnet wire from slipping when it comes close to the edges?
Best regards!
in the past (i.e. in my youth) I've successfully wound dozens of transformers, both power and output transformers, as well as chokes. I did it the, say, German way, using flanged bobbins and serrated insulation foils. Both are (were?) very common here and make winding a relatively easy-peasy job.
Now I've harvested quite a number of power transformers from cheesy transistorized Hammond organs. Unfortunately, most of them feature 115 Vac primary windings, hence aren't much of use for me in their present state. So I'm about to rewind (some of) them. Even more unfortunately they weren't wound on flanged bobbins, just rectangular tubes are there.
That makes me scratching my head now. What precautions do I need to do to prevent the magnet wire from slipping when it comes close to the edges?
Best regards!
Clamp the bobbin between two temporary flanges, made for example from two squares of PCB material with a hole in the center.
Use the holes to pass a threaded rod, both to tighten the assembly and as a means to attach it to a vice or a drill chuck during the winding.
During the winding, regularly put a dab of cyanoacrylic glue here and there, especially on the turns closest to the flanges.
Leave a reasonable gap between the winding and the edges, to avoid insulation issues.
Alternatively, you can completely avoid rewinding by using this method:
Here is an elegant (insane?) way of converting 220V to 110V
but do it at your own risks!
Clamp the bobbin between two temporary flanges, made for example from two squares of PCB material with a hole in the center.
Use the holes to pass a threaded rod, both to tighten the assembly and as a means to attach it to a vice or a drill chuck during the winding.
During the winding, regularly put a dab of cyanoacrylic glue here and there, especially on the turns closest to the flanges.
Leave a reasonable gap between the winding and the edges, to avoid insulation issues.
Alternatively, you can completely avoid rewinding by using this method:
Here is an elegant (insane?) way of converting 220V to 110V
but do it at your own risks!
I'm still wondering how the manufacturers do/did their flangeless winding job. Did they also put 'a dab of cyanoacrylic glue here and there'? Somewhat hard to believe, 'cause this makes it a very time consuming procedure .
The specific power tranny I have in mind won't ever be a power tranny again. Instead, I intend to use it's laminations to built an output transformer. Hence, your elegant way of converting voltages sadly won't be applicable.
Another thought: Would it be possible for two indentical PT's to connect their 115 Vac primaries and also their secondaries in series, rectify the secondaries with a single bridge to get a dual rail PSU?
Best regards!
.The specific power tranny I have in mind won't ever be a power tranny again. Instead, I intend to use it's laminations to built an output transformer. Hence, your elegant way of converting voltages sadly won't be applicable
.Another thought: Would it be possible for two indentical PT's to connect their 115 Vac primaries and also their secondaries in series, rectify the secondaries with a single bridge to get a dual rail PSU?
Best regards!
They had (and still have) different techniques, but no cyanoacrylic. One was to use separator sheets between layers, another was to use a temporary coil former and self thermo-glueing enamel, or post-impregnation.I'm still wondering how the manufacturers do/did their flangeless winding job. Did they also put 'a dab of cyanoacrylic glue here and there'? Somewhat hard to believe, 'cause this makes it a very time consuming procedure
For large wire diameters, the winding can be completely self-supporting, thanks to the constant tension of the wire (professional winding machines keep the wire accurately tensed during the whole winding process)
Yes, it is perfectly legit to do that