Patchwork Reloaded: Circuit Optimization and Board Layout.

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#541
MJL21193 said:
It used to be easier to find these things here too, but more and more the small stores are getting swallowed up by big ones and the ones that are left need to trim the inventory to compete.
The best bet here for most of this stuff is to find it and buy it on the internet.
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Same here in the U.S. too. The Lowe's and Home Depot stores have almost completely taken over what traditional hardware stores used to do (except the Ace Hardware chain). But those places are oriented toward home building and upgrading, not electronics. With the housing slump, they are scaling back. I needed a new fuse for my DVM and none of those places had one. I had to order it online. And if you don't know what you're looking for...
 
#542
by pingrs -We can find terminal blocks in any old hardware or DIY shop here
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😕 What are those. It looks like 15 or 20 years
ago in knoxville ,tn. ..there were audio outlets and TV
shops/hobby shops , I see the old signs behind the boarded up lots
and storefronts. Now , in the middle of the city ,all that
remains are the bank towers, then 3 miles of boarded up
former small businesses and shops, then the home depot/
lowes/walmart "zone" 5 miles from the center.

Only 3 out of 17 of my local businesses still exist (2 convenience
stores and a pawnshop/title loan) all others have "for lease".
They even built a brand new office condo next door .. not
one unit has sold.. 😕 in 2 years..

Dumpster diving and the internet are the only sources ,even
most of the local "cellular shack's" don't even carry solder or
parts here.
 
#543
Hi MJL21193,
Jane is allright; javascript:smilie(':hbeat:') Married 10 years ago.
Tired of running around in the jungle and found it time to settle down.
(No joke here; It's the truth!!!)

It seems that these connection blocks are so hard to find?
Here in Belgium (and Europe I suppose) they are to available inevery DIY store. Cheap and in various sizes.

Strange you do not find them way back there.
Maybe the jury whas right, then back in the time...

I have to build a Home Entertainment Center wih seperate amps.
This looks like a nice model to start with.

Cheers, Tarzan
 
#544
Over here those terminal strips are common electrical items, often used for joining together flex and such like. You also find it in some types of light fitting. It's also used a lot for in-car work.

It's really handy to an electronics DIYer, i'd be lost without it!
 
#545
Pingrs said:
terminal blocks
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The bigger ones are nice.
I prefer the dual in-line screw types (4 screws in a row), can't ficking find a piccy on the hard discs just right now.
 

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#546
andy_c said:
And if you don't know what you're looking for...
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That was my problem before (you know, before I became amp builder extraordinaire 😀 ). I wound up buying a bunch of stuff that was the wrong voltage, the wrong size, the wrong type. Finding these things on the big guys sites is difficult too - it took me nearly an hour to track down board mount spade connectors at Digikey (1285K-ND terminal quickfit). :whazzat:

Tarzan said:

Jane is allright; javascript:smilie(':hbeat:') Married 10 years ago.
Tired of running around in the jungle and found it time to settle down.
(No joke here; It's the truth!!!)

I have to build a Home Entertainment Center wih seperate amps.
This looks like a nice model to start with.
Click to expand...

Hi Tarzan,
Yes, the jungle scene gets old quick. Give me a steaming mug of coffee or a cold beer and a huge TV over the jungle any day. 🙂
I'm up for the idea of chasing a pretty girl around in my loincloth though...
:devilr:

It's a great amp if I do say so, and it has the added benefit of being compact AND powerful. Sounds excellent, runs like a precision timepiece and hey, it looks good too. 😀
 
#547
jacco vermeulen said:


The bigger ones are nice.
I prefer the dual in-line screw types (4 screws in a row), can't ficking find a piccy on the hard discs just right now.
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Jacco, let's make a deal. I'll send you 2 of my ex wives (they are still viable specimens, with a few miles life on them) for a 2 kilo box of you assorted goodies! Howsa'bout that? 😀 Don't forget a few of the marshal NEC's...😉

I have finished the supply wiring and the input wiring on one side. Nothing spectacular, but steady progress.

Picture1060.jpg


I have some paint touch ups to do when everything is complete. I considered painting the heatsinks black, but I'm still undecided. I'll wait until I have the top figured out and made up before I decide.
 
#548
andy_c said:


Same here in the U.S. too. The Lowe's and Home Depot stores have almost completely taken over what traditional hardware stores used to do (except the Ace Hardware chain). But those places are oriented toward home building and upgrading, not electronics. With the housing slump, they are scaling back. I needed a new fuse for my DVM and none of those places had one. I had to order it online. And if you don't know what you're looking for...
Click to expand...


Just about any electrical wholesaler should sell those terminal strips. Over here I can even get them at the local "electronics" shop that mostly sells plama TV's, computers and novelty gizmos.

Cheers,
Glen
 
#549
MJL21193 said:
...
I have made up a soft start for the power supply and it is very simple. It uses a 10 amp thermistor that is bypassed with a pair of relays (in parallel). The design is adapted from a National Semi power supply ap note and uses the power supply voltage to close the relays.

The 10 resistors and zener cut the rail voltage to 12VDC. It has no delay, but relies on the fact that the power supply needs to be up before the relays close. I can add a delay if I find this is not working as expected.
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Nice amp John - really great work! :up:

Could please you point me to the National application note related to your soft start? I am toying with a new power supply and that would be a great (simple) addition to it.

Thanks!
 
#554
dudaindc said:


Nice amp John - really great work! :up:

Could please you point me to the National application note related to your soft start? I am toying with a new power supply and that would be a great (simple) addition to it.

Thanks!
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Thanks duda,
Sorry for the slow response - I've been away.
The link I can't find but I did save the pdf. Send me an email and I'll forward it to you.


Bigun said:
Wow, that photo John is an inspiration.

I am busy sorting out a BOM for parts for my TGM amp which will also go into a multi-channel box and I hope it turns out half as neat as yours.
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Thanks Gareth,
Projects like these are large undertakings, demanding huge hunks of time and a not inconsiderable amount of money. I'm fortunate to have some of each but I've been pressed for time lately. I have a few odds and ends before the amp is fully complete.
The best advise I can give for your own project is to plan and re-plan every detail and don't rush it. You'll be more satisfied with the results if you have made every effort (within reason) to ensure what you are not disappointed with the results.
 
#555
MJL21193 said:

I'm not sure. I didn't buy it. It is not very good, so Jobmate would fit. I had 3 or 4 of them (given to me) and all but one is broken - the plastic breaks when you tighten it. Don't know my own strength when I squeeze the grip, I guess.
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Just had the same thing happen to me today. I guess they aren't kidding when they say it's light-duty, but how else are you supposed to use it?
 
#559
Re: patchwork

454Casull said:
Arctic Silver 5 is fairly cheap and is a relatively good thermal conductor.
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Trying to catch up...
I like to experiment. I tried the lube stick (pic posted on previous pages) to see how well it performs and so far, I'm not disappointed. It was cheap and best of all easy to use and not messy. Easy as using a glue stick - just rub it on the back of the device, stick on the mica and rub it on that. I'm seeing EXCELLENT heat transfer to the heatsink.
A winner. :up:

andrewlebon said:
greetings can patchwork be used for 4 ohms load and
if it can be used what will be it output.
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Hi andrewlebon,
Yes, 4 ohms is ok. Reducing the rail voltage to +/-42V will be the safest bet and adjusting the gain by increasing R26. Output can be 140+watts into 4 ohms.
 
#560
454Casull said:

Just had the same thing happen to me today. I guess they aren't kidding when they say it's light-duty, but how else are you supposed to use it?
Click to expand...


They are those "imitation" tools. Look like tools but break as soon as you use them. They seem like a good deal - cheap.


I've hooked up the soft start and it works fine BUT the delay can use some improvement. To that end, I've designed and built a delay board that will close the relay ~1 second after the power turns on. This allows the thermistor to fully absorb the inrush current.
Here's the circuit:

TIMER.png


Yes, big transistors 😱 but I have a bunch of these and this is as good a place to use them as any. Simple and effective.

The board, tested and working:

Picture1063.jpg


It will be installed beside the soft start board.
I still need to create a permanent tap off the power supplies positive leg to run this. I failed to include it during the PS board layout.
 
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