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C64 Computer Saver from Ray Carlsen

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Ray Carlsen, veteran Commodore repair technician, is now selling Computer Saver (an improved version of his original Computer Saver, the schematic of which had been on his website for years). Like the original, his new Computer Saver functions as a voltage limiter when plugged in-line between the C64 and the C64 power supply. Read what Ray says about his product --

 

---------------- Original Message -----------------

From: "Ray Carlsen" <rcarlsen(at)tds.net>

Date: Fri, June 21, 2013 11:53 pm

---------------------------------------------------

 

Hi,

 

Photos of the construction of those savers are on my site --http://personalpages.tds.net/~rcarlsen/cbm/c64/SAVER/EXTERNAL/

 

AN EXTERNAL "COMPUTER SAVER" PROTECTION DEVICE FOR THE C64

 

This shows a small run of the Computer Saver I designed. It is made to be installed between any C64 and its power supply. The two LED's on the Saver case are indicators of the PS status. The LED on the left monitors the 9VAC from the supply and it should be on all the time the PS is plugged in to AC power, whether the computer is on or off. The other LED (marked "failsafe") is normally off. It only comes on if the PS fails due to a shorted internal regulator. That fault is what damages chips in the computer, most often the RAM. Since there is already an LED on the computer case which

monitors the regulated +5VDC, one on the Saver was considered unnecessary.

 

The cost of the Saver is $50 US. That price could be reduced somewhat with a larger production run, but unless there is greater interest in this device, I'm not ready to tool up for that. More than half that amount was spent for parts, including shipping. Any time something is hand-made and parts are individually purchased, the price of the end product will be higher than people expect. The construction of a stand-alone device is normally higher than the same circuit built into a computer such as the C64. That's due to the added expense of a case, cable wire and connectors as well as the added time it takes to assemble the device. There are few shortcuts, so the price is firm.

 

One version of this device has been seen for sale on the Internet, but the builder likely didn't consider one thing when constructing it. Most importantly, the "trip" point of the Saver is critical. That is the exact voltage level at which the device cuts off power to the computer. Because of variable tolerances of some of the components, the trip point must be manually set with an accurate voltmeter and variable bench power supply. This setting is done as a last step after the device is built. If it is set too high, the computer is still at risk, and if too low, the device may cut power with a normal power supply that has a slightly abnormal but acceptable output level during a "no load" condition such as when the supply is plugged in to AC power but the computer is turned off. Keeping those voltage limits in mind, I found the optimum trip point to be between 5.3 and 5.4 volts DC. RAM chips have an absolute maximum rating of 5.5 volts, so the protector -must- be set below that value.

 

Because the protectors LED's are on its case, I decided to make the cable between it and the computer rather short, about one foot long, so those LED's can be monitored. If desired, that cable can be made longer so the protector is off the desktop. However, very long cables will reduce the voltage at the computer since it draws nearly one Amp in normal operation. The short cable seemed like the best arrangement.

 

Ray

 

----------

 

See Computer Saver on exhibit at CommVEx,

Robert Bernardo

Fresno Commodore User Group

http://videocam.net.au/fcug

July 27-28 Commodore Vegas Expo v9 -

http://www.portcommodore.com/commvex

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You'd think someone would be producing PSUs that don't fail, instead of making the crappy vintage ones safer.

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You'd think someone would be producing PSUs that don't fail...

Heh, the repair tech for The Other Group of Amigoids in San Jose, California takes C64 power supplies and upgrades them to modern components so that they run cooler, run reliably, and output more power than the originals.

 

Having a few of those,

Robert Bernardo

Fresno Commodore User Group

http://videocam.net.au/fcug

July 27-28 Commodore Vegas Expo v9 -

http://www.portcommodore.com/commvex

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Heh, the repair tech for The Other Group of Amigoids in San Jose, California takes C64 power supplies and upgrades them to modern components so that they run cooler, run reliably, and output more power than the originals.

 

That modernized power supply sounds pretty nice. A Google search revealed TOGA to be at http://www.calweb.com/~rabel1/ but I couldn't find information about a modernized PSU. Is this something available to the general public or only to TOGA members and/or locals?

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really he could spin a PCB and get 10 made up for 10 bucks + shipping and save a lot of hassle, theres maybe 5 bucks worth of parts even in small bulk quantity, charge 2 bucks for the PCB and add some overhead for labor.

 

its a relay, some resistors, zener diode, LEDs, a box and connectors, the box and connectors being the most expensive parts if he was not manually dead bugging it and exploding his labor investment.

 

take my virtual serial host project, I have nearly a couple dozen parts that make up a small computer talking to an SD card to emulate PC software to communicate to an apple II and have an official asking price of 40$ + shipping while only doing very small batches of 10. seems like a lot of effort which makes this thing overly expensive for what it actually does.

 

electronic devices dont have to be mass produced to achieve a decent price ratio, its about exploring your options, yea 50 bucks seems perfectly fair considering this thing is hand made in just about every aspect, but in reality a evening poking at digikey and a cad program could reduce the physical labor and cost dramaticly, even in batches of 10, it could be a 20 dollar or less uint, that reqires much less effort, better quality and more "street cred" potentially selling more ... saving more systems which I gather is the entire point.

 

I actually work in mass production of electronic circuits, and if the maker is interested in making his life easier, his product cheaper, more reliable, and more available, I am more than willing to share what I know to help make this a need more than a niche want.

Edited by Osgeld

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Ray Carlsen now offers three versions of the Computer Saver. There is the $25 Computer Saver module that a user can install in their own computer, there is the $35 Computer Saver cable (without LED indicators) version, and there is the $50, original, case-mounted Computer Saver (with LED indicators). To read more about Computer Saver and to see pictures, go to




Truly,

Robert Bernardo

Fresno Commodore User Group


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That modernized power supply sounds pretty nice. A Google search revealed TOGA to be at http://www.calweb.com/~rabel1/ but I couldn't find information about a modernized PSU. Is this something available to the general public or only to TOGA members and/or locals?

I only tend to do them for friends/locals or for machines that I work on or sell. I honestly don't trust stock C64 PSUs anymore because of their stupid partial failure modes - one can get just bad enough to where it runs one computer and not another, and troubleshooting C64s is difficult enough without having to worry about the PSU.

 

They're not too hard to do, really - find the best, smallest +5V PSU you can, find a 9V AC brick that puts out the right amount of current, get them out of their existing shells, stick them in bigger shells and wire them up correctly. A select few C64 PSUs are screwed together and the shell can be reused, but most are idiotic epoxy-filled bricks and have to be smashed open.

 

I tend to re-use the existing cable going from the PSU to the computer as often as I can because I really hate soldering to DIN connectors. On average, it takes 3 PSUs to upgrade a C64 PSU - a +5V unit, a ~9V brick, and a shell donor PSU that's big enough to house both but is otherwise worthless or dead. My +5V power supplies tend to come from discarded networking gear, the 9V bricks are usually from later US Robotics modems, and the shells I use are from larger external units that have been junked. (Ironically, project boxes tend to be much more expensive than just stealing the shell off of something else.)

 

Since the screw holes for the original PCB that was in the shell donor rarely line up with the screw holes for the donor +5V PCB, and since there's no real way to secure the 9VAC transformer without screws and a frame, I usually wind up anchoring both to the inside of the new shell with tons and tons of double-stick foam. It tends to be pretty secure but I sometimes worry about it coming loose. If I have the space, I try to wire up the cable going from the PSU to the computer so that it can easily be swapped out. This way one PSU could theoretically be used to run a C64, C128 or Plus/4 just by opening it up and swapping the cable.

 

Making up a custom PCB for this is overkill, and basically reinventing the wheel. To do this on a commercial scale, you'd mainly need to source a large number of cheap, newer (and therefore smaller and more efficient) +5 volt power supplies, preferably as bare boards. You'd also need to source a large number of 9V AC transformers that can put out at least 1 amp and aren't too big to fit into whatever kind of case you're going to use. Then you'd need to source the shells, cables, connectors and other bits and pieces to fit it all together.

 

What I'd love to find is a +9V AC transformer that can be switched between 110 and 220 volts, because that would make it possible to build a PSU that would work anywhere. Any DC power supply made in the last decade or so is going to be auto-switching, but AC doesn't work that way and the vast majority of the transformers out there can only take one input voltage anyway. Commodore even made a couple of C64 PSUs that were switchable between 110 and 220, but they appear to have only been sold in certain markets.

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They aren't really sold anywhere. Ray made a batch and others have made a few upon request. People doesn't seem to understand why it's good equipment to have.
I have built a few, it would be a lot easier with a dedicated PCB. I tried making a more modern version with an exact trip point and electronic control but the power transistor steals a few tenths of the voltage and my LOAD-IT datassette reacted to it as the voltage got low. All LEDs lit up and made the display useless. So it was not a good solution, the relay is better, at least if you have voltage sensitive equipment.

Here are my versions, first two are the small modern version, optionally it could be placed on a wire:
IMG_1010.jpg Img_1014_ed.jpg

This is similar to the one I use myself (sold this on eBay), but mine has two wires and wire mounted connectors. I think Ray's version with the metal framed DIN connector is pretty nice.
IMG_7376.jpg

Buying parts for 10 or 20 of these would probably give a better price, Ray's $50 price is pretty much the same as I charged my buyers.

Edited by e5frog

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efrog wrote:

 

> Ray made a batch and others have made a few upon request.

 

Ray has more than a few.

 

> ...Ray's $50 price is pretty much the same as I charged my buyers.

 

From Ray, "One other thing I should mention about the Savers... There are three versions and they all have the red "fail-safe" LED. The module alone ($25) is designed for user installation in their own C64, VIC20CR or Plus/4. I install one in every repair job now.

 

The stand-alone cable Saver ($35) is a complete unit that plugs between the computer and PS. Its LED pokes out the side of the shrink tubing that covers the module.

 

Lastly, the deluxe Saver ($50) in the plastic case has both red fail-safe and green 9VAC confidence LEDs."

 

Truly,

Robert Bernardo

Fresno Commodore User Group

http://videocam.net.au/fcug

July 26-27 Commodore Vegas Expo v10 -

http://www.portcommodore.com/commvex

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I have one of the external Power Savers, and have installed internal ones in every one that I have fixed. Nothing makes you feel better than knowing that the old brick isn't going to fry your RAM!

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Wouldn't it be cheaper to use a more modern parts to make a full replacement power supply? A fuse and switch (optional, many people uses power strips these day that already have switch) on primary side of a basic transformer that step down from mains to 9v AC, full wave rectifier, caps to filter out ripples after rectifier, and a 5v DC-DC converter. On the 9VAC one could build a crowbar circuit that blows fuse and shuts down the power supply if something goes wrong. With good components this could costs about the same as the saver but outlast any Commodore made C=64 power supply.

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Wouldn't it be cheaper to use a more modern parts to make a full replacement power supply? A fuse and switch (optional, many people uses power strips these day that already have switch) on primary side of a basic transformer that step down from mains to 9v AC, full wave rectifier, caps to filter out ripples after rectifier, and a 5v DC-DC converter. On the 9VAC one could build a crowbar circuit that blows fuse and shuts down the power supply if something goes wrong. With good components this could costs about the same as the saver but outlast any Commodore made C=64 power supply.

 

Well, in this case, I think this solution is for people that aren't willing/able to build their own power supply. I got mine because I have to test a lot of systems, and usually those systems come with classic 'bricks'. This allows the user to keep what they have, and never worry about the classic brick killing their RAM.

 

I also built Ray's load tester for the power supplies so I can do some testing on them as far as voltage being correct over a long period of time.

 

According to Ray, the older bricks always fail the same way, so this saver he makes is setup to prevent that failure from causing damage on the 5VDC line. The 9VAC line comes directly off the transformer, and isn't likely to be bad - unless the PS has been shorted, then the internal fuse blows.

 

I have a couple of the power supplies that came with the RAM expansion, and they don't fail like the old style bricks do - but then again, the size of the brick is almost double the size of the old ones! Also, this solution is not for everyone because those power supplies are tough to find, and pretty expensive!

Edited by TheRealAnubis

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Well, in this case, I think this solution is for people that aren't willing/able to build their own power supply. I got mine because I have to test a lot of systems, and usually those systems come with classic 'bricks'. This allows the user to keep what they have, and never worry about the classic brick killing their RAM.

 

Heck, I'd give anything a shot if I had a parts list to go off of. Half the issues I run into when tackling projects like these is knowing exactly what components to purchase. Some schematics leave something to be desired for electronic noobs. We need a bit of extra help but with a little of that we'll become better and then be able to help other noobs..and so on.

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Ahhh... fond memories of "disassembling" a Commodore 64 brick power supply. With a sledge hammer.

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Thanks I was making the mistake by using the actual not hand drawn schematic that doesn't specify the relay value. Silly me. :-)

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You could build that power saver in a stand alone box using male and female DIN plug so it can be moved to different C64's. Just wire the 9vAC straight through and connect the shield on both end.

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You could build that power saver in a stand alone box using male and female DIN plug so it can be moved to different C64's. Just wire the 9vAC straight through and connect the shield on both end.

 

Yep! That's the kind I got from Ray. If you have many machines, just move it to whatever one you're using at the moment..

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So, it was Commodore day at the SCRS this weekend and there was some discussion about making a brand new c64 power supple from all new parts as well as updating the circuit. Seems like this sounds like a more professional looking idea than creating a seperate box. Did this idea ever get built? With 3d printing, if more space is needed in the power supply, that seems like an easy way to create a professional looking PS.

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It's not difficult to build one, if you're going to sell it though you need insurances and certification, it's not allowed for anyone to just slap something together and sell. That's why an already existing power supply with an adapter box is a simpler idea, no 110V or 230V is touched only the low voltage on the output. A lot easier to make and sell without needing tests and so on.

Edited by e5frog

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