I've been putting some thought into power supplies, especially the high current variety. Modern tech has gone over to switchers for the most part. They are small, lightweight, and do the job.
Note: some of the following circuits I'll be discussing only pass muster because they do have a isolation transformer. The voltages and currents are NOT safe, and should be handled by experienced hobbyists.
One of the secrets for switchers is the use of torrid transformers instead of the bulky 50/60Hz units used in many wall warts. The latter are easy to use and pretty safe, but they are big chunks of iron and heavy. Torrid transformers can handle some respectable currents, but not at low frequencies.
So we need a circuit to make a high frequency medium current feed for a torrid. Not too difficult, fully rectified AC with nominal filtering will make 180VDC. Again, if this voltage were to be used directly this thread would be shut down in a heart beat, but the plan is to use it in a sealed circuit.
I am a math brick, to steal a phrase from a friend. I'm debating what the best frequency and windings for a home brewed torrid would be. A 180V P-P square wave at 1A would translate to 24V at 7.5A. A simple circuit such as this should suffice.
Regulation could also be accomplished by simply adding an optocoupler to turn the oscillator on and off with a simple comparator.
Which brings me to regulators, a different subject but related.
My first though probably will not work, though I am tempted to build it and see. This is because of one of the odd problems with MOSFETs, where they require a really substantial drive current to turn them and off quickly. The circuit to turn this on is adequate, but not so for turning it off. 10KΩ will probably not be enough.
To solve this problem I would probably use something like this design.
This is not the first thread I have done on switching power supply regulators, but I have a bit more experience under my belt. Some of this may wind up in the ebook, after experimentation. This is where this project I showed would come in handy.
Project : Electronic Load
Basically I'm putting this thread out for discussion and questions. I'm always willing to learn, though as I get older it does seem harder. I joke with my son, my Alzheimers is firmly under control. For some reason he doesn't find that funny.
Edit: People may wonder what the .zip attachment is about. I work from quite a few computers, so I'm using this first post as a stash point for my various drawings. Basically work in progress.
Note: some of the following circuits I'll be discussing only pass muster because they do have a isolation transformer. The voltages and currents are NOT safe, and should be handled by experienced hobbyists.
One of the secrets for switchers is the use of torrid transformers instead of the bulky 50/60Hz units used in many wall warts. The latter are easy to use and pretty safe, but they are big chunks of iron and heavy. Torrid transformers can handle some respectable currents, but not at low frequencies.
So we need a circuit to make a high frequency medium current feed for a torrid. Not too difficult, fully rectified AC with nominal filtering will make 180VDC. Again, if this voltage were to be used directly this thread would be shut down in a heart beat, but the plan is to use it in a sealed circuit.
I am a math brick, to steal a phrase from a friend. I'm debating what the best frequency and windings for a home brewed torrid would be. A 180V P-P square wave at 1A would translate to 24V at 7.5A. A simple circuit such as this should suffice.
Regulation could also be accomplished by simply adding an optocoupler to turn the oscillator on and off with a simple comparator.
Which brings me to regulators, a different subject but related.
My first though probably will not work, though I am tempted to build it and see. This is because of one of the odd problems with MOSFETs, where they require a really substantial drive current to turn them and off quickly. The circuit to turn this on is adequate, but not so for turning it off. 10KΩ will probably not be enough.
To solve this problem I would probably use something like this design.
This is not the first thread I have done on switching power supply regulators, but I have a bit more experience under my belt. Some of this may wind up in the ebook, after experimentation. This is where this project I showed would come in handy.
Project : Electronic Load
Basically I'm putting this thread out for discussion and questions. I'm always willing to learn, though as I get older it does seem harder. I joke with my son, my Alzheimers is firmly under control. For some reason he doesn't find that funny.
Edit: People may wonder what the .zip attachment is about. I work from quite a few computers, so I'm using this first post as a stash point for my various drawings. Basically work in progress.
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