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Maker Pro

I'm getting there, slowly

JohnP

Oct 22, 2016
31
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Oct 22, 2016
Messages
31
I hope some of you remember me. I posted a thread re a 2N3055 power supply I was making - or trying to. I decided to take time away from the Forum to learn a little more about electronics. My 50 year gap was just too much to catch up with todays electronics hobby.
It was due to your help I realised that I still had the 'urg'. I have built 2 power supplies. One has a fixed output of 26V and around 7A. The other uses 2 TIP35C's driven by an LM338. Both are in old PC power supply cases. These are purely as a learning exercise. They have been on a scope and I was pleased to see they were 'quite reasonable'. They are now going to be taken apart for hopefully better boxes and a neater setup, etc.
I have also started my 3rd power supply. It's a much modified Monacor amp that died due to beer. I intend using the 4 x TIP35C and 27V 8.88A toroidal transformer. The 40V DC around 5A transformer in the Monacor is going to be used to drive the TDA7498 and E version and the TPA3116D2 D Class amps I have (with just V adjustment). Unfortunately I caught a terrible affliction, it's called EBAY. The circuit shown many of you will recognise as an old faithful. Just another step towards ?
I also have quite a few buck converters of almost every type I might feasibly need. That's a mains to 24V DC 8.5A behind the Monacor.
I fully appreciate that kit from China has a bad reputation. None of the essential parts have come from there but I do intend to try things like power transistors, etc. The items I have used have so far done their job including the linear Tenma power supply.
I will post from time to time and no doubt I'll run into problems that I hope you can find the time to answer.
I just wanted to let you know your time was not wasted.
Cheers amd a belated Happy New Year to you all.
 

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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
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The most glaring issue I see is that the connections to the bridge rectifier in the first image (RHS) are not insulated and are quite close to an exposed heatsink. At the very least, slide a piece of insulating material between the heatsink and the leads.

In general, the quality of insulation is poor.

I didn't take a close look at the mains wiring, but seeing a what appears to be a LED in close proximity to the mains input connector has me a little concerned.
 

JohnP

Oct 22, 2016
31
Joined
Oct 22, 2016
Messages
31
The most glaring issue I see is that the connections to the bridge rectifier in the first image (RHS) are not insulated and are quite close to an exposed heatsink. At the very least, slide a piece of insulating material between the heatsink and the leads.

In general, the quality of insulation is poor.

I didn't take a close look at the mains wiring, but seeing a what appears to be a LED in close proximity to the mains input connector has me a little concerned.

I agree with you 100%. The whole thing was a lashup purely as an excersize. After my 245V AC belt I was a little more carefull. Both of these power supples were far too cramped with caps and protection diodes missing, wire that is too thin, awful soldering, etc., etc. I ran them for an hour with the highest current I thought safe. They also ran for a short while when a friend brought his oscilloscope to show me briefly how they work and check the outputs. He was surprised - but not as much as I was. They will now be stripped and rebuilt and I will post photo's for critical inspection. Boxes are a problem so I may have to make a 'brake' to bend my own. Thank you very much for your reply.
 

Audioguru

Sep 24, 2016
3,656
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Sep 24, 2016
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3,656
I am sorry to hear that your power supply died from drinking too much beer and got alcohol poisoning.
I had a dog that drank my beer when I had it in a mug, but since changing to beer in cans my dog couldn't "bottom up" it.
 

Cannonball

May 6, 2017
193
Joined
May 6, 2017
Messages
193
I like your spirit. Be careful with the supply voltage though.

Keep the beer out of reach, an intoxicated power supply may also take up a bad smoking habit.

Electronics is FUN.
 

JohnP

Oct 22, 2016
31
Joined
Oct 22, 2016
Messages
31
I am sorry to hear that your power supply died from drinking too much beer and got alcohol poisoning.
I had a dog that drank my beer when I had it in a mug, but since changing to beer in cans my dog couldn't "bottom up" it.

Hello. The 'power supply' was a pub 100V 120W mono line amp. It had Monacor's super no fan cooling system. Vents below the fins in the internal heat sink in the floor and a perforated roof. Ideal system for beer cooling, it could even drain away. There were signs of over heating on the main PCB, the thermal limiting device was going thermal. It powered up but I decided the rather sturdy case would be a nice place to start my first real power supply. The new 27V DC 6.0A toroidal will drive the 4 x TIP35C - 40W each is a lot. Thermal regulatorion and fan control, resetting fuses, current control, etc will help. Our whippet Elli likes Marmite, lumps of it.
 
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sureshot

Jul 7, 2012
234
Joined
Jul 7, 2012
Messages
234
Very cool, looks like we have similar interests. Nice size and reuse of the atx cases.
 
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