If so, which would sound better, this or MJL? Last edited by Piisami; 18th May at PM. Reason: added link. The original bipolar transistors were obsolete around 15 years ago. However, On Semi have expanded this type range with additional packages like TOP3 and also higher voltage versions for use in large amplifiers. Any seller of power transistors will stock or obtain these popular products.
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Thanks so much for your time. Scroll to continue with content. Not good on price, but simple to use. You might have some good luck with the MJE series parts. That was fast. Experimentonomen Joined Feb 16, Be very weary with NTE parts, they are known to be remarked devices that does not match the original parts spec what so ever. Well, the deed is done. I move fast.
It's a character flaw, or the fact that I'm where the town where the phrase "New York Second" originated Hopefully I'll be ok. It's for a power supply Don't forget the HUGE heatsinks and fans.
Yeah, I'll be attaching it to the aluminum chassis for heatsinking I also picked up some mica and thermal compound. I think I got the wrong form factor for the mica, but I bet I can make it work The metal chassis is not "heatsinking" when you are using W 15A power transistors! What output current will you be running and what is the linear voltage drop difference between Vin and Vout? That can be used to calculate the worst case heat dissipation in the power transistors.
If you post a schematic diagram that will help a lot. I'm new to this.. This does give me an opportunity to try to explain what the project is, which may be better for me than for you. In the end, the question of whether using the chassis for heat dissipation is wise or not may be overshadowed by my obvious ignorance and the fact that I'm sure that there are better designs for a power supply.
This design seems good for learning though. There is a chapter later in the book with some mods to allow for better voltage regulation It goes into current limit mode at about 1. This section, regulates? Again, please forgive my ignorance. For the "transistor-y section": Materials:.
Last edited: May 7, The power you need to get rid of is 45 watts at the worst. This puts you in the position of learning heat flow.
Resistance to heat flow is called, "theta" and this resistance is always defined as between two places. Theta junction to case of the transistor , theta case to heat sink, theta heat sink to air, all add together.
The datasheet of the transistors will tell you most of this, like maximum temperature allowed and the heat flow resistance of the transistor. Long story short: You're going to be using one or two chunks of aluminum about the size of your fist. Wonder if I understood the first part of that design correctly as far as Vin goes. That said, I've got a nice metal enclosure on order.
You really think the book is that far off? Maybe I need to look and double check I understand the front end of that circuit. I wonder if the mods he has later in the book deal with that. He does mention that it's a basic design Later in the book he talks about replacing Q3 and Q4 with Darlington pairs as one possible improvement.
Another improvement he talks about involves this schematic, showing only the positive regulator Hello, Have a good look at the transformers connections. I made some remarks in the schematic you posted:. He makes a point to really show how to wire them so they are in phase. I assume the book also explains some of the circuits?
Building a regulated supply as a learning exercise is a good way to understand much electronics and you hopefully end up with a useful piece of kit. I have certainly built more PSUs than another other type of circuit over the years. The problem is this. The gain of the pass transistors is low which is why Darlingtons are recommended as an improvement and the supply differential amp gain is also low Which is why he recommended an op amp. To compensate for this the raw input supply is high so that Q3 and Q4 can draw enough current through R1 and R2 to supply the pass transistor base drive and and also their own needs.
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2SC3281 Bipolar Transistor
2SC3281 Datasheet, Equivalent, Cross Reference Search