[ngr1]

Hello, can I use G201 drives w/ 48VDC/10A P/S?

I know the Gecko specs state a maximum of 7amps so does this mean I have to lower the output of my P/S? If so how would this be done?

My stepper motors are rated for 48VDC @ 8.1Amps.

Thanks... Norman

[ger21]

The 7 amps is what the Gecko can deliver to the motor. It will only draw what it needs from the power supply, so the 10a supply won't be a problem

[Mariss Freimanis]

A power supply is just like a bank account. If you have $10 in the account, you can write a $7 check. The remaining $3 can be spent anyway you wish or be left there. Just don't write a $10 check on a $7 account. The Law says your supply will burn down if you try.:-)

Mariss

[ViperTX]

Mariss....so the FET's will never breakdown??

[Mariss Freimanis]

Jeez,.. apples and oranges with that question. Reading between the lines, I think I understand what you are asking.:-) The power supply current rating has nothing to do with that.

The following is just meant to be fun:

MOSFETs "breakdown" as in "explode", let the "magic smoke" out, etc. for 3 reasons:

1) You over-voltage them. 114 to 116 volts DC does a fine job. Make sure you rev-up your big NEMA-42 motor running at 80VDC to full speed before you stall it. Make sure you have a tiny bulk filter capacitor; you don't want a big cap absorbing the returned energy. That makes it harder to put the sweet 116VDC or so you need on the drive to get that satisfying crackle and the nice puff of smoke your'e after. By all means don't use a fuse; it ruins the after-smoke arcing and flames as the drive charrs to a crisp.

2) You over-current them. About 60 to 100 Amps for more than 1/10 of a second is about right. A good short-circuit on a motor lead or between windings does very well. Don't use a G202 though, it has a nasty short-circuit protect circuit that will try to thwart you. G201s blow real nice here, no protection at all. Sweet! Don't forget about the fuse part, use it and lose half the fun.

3) You cook them. Guaranteed to blow when the case temperature hits 130 C or so. Don't forget to baste them. Avoid getting any heatsink grease between the drive and the heatsink. That increases the baking 'till done time. Take bets from your friends on how long your 4" by 4" by 0.05" steel "heatsink" will prolong the agony. Hint: 5 minutes.

Set the drive to 7A, and do NOT use the required 470uF/100V cap. A rare but fun crowd-pleaser is in store. Watch as the drive cap explodes spewing aluminum foil confetti all over the place in a tasteful aluminum chloride steam explosion. Takes a while but it's worth the wait.

For the more adventurous:

1) Try reversing power supply polarity. You know; '+' where '-' is supposed to go, visa versa. Do not use a wimpy supply; get something big rated 85VDC at 25A. It takes real power to make real fireworks. Hook-up 4 drives for maximum effect. Take bets on which one goes first; don't blink though, it'll be fast. Scrape up the remains, pour them in a box and send them back with a note they were DOA.

2) Pick an old crapped-out 30 year-old motor with a shorted winding. Old Bridgeport NEMA-42s from the late '60s and '70s are a terrific source. The kind you get on ebay $1.99. Order a dozen or so G201s (avoid the G202s, they are no fun). Hook them up to the dead beast and throw the power switch. Check with your friends about the sounds the G201s make as they smoke. Pick the one making the funniest sound. The current record is 12 in a row; that should be easily beatable. Scrape up the remains, pour them in a box and send them back with a note they were DOA.

3) Do not try this at home. A trained professional did this: Take 240 VAC and hook it up to the supply inputs. Find out what these puppies can do when there is real power going into them (you can use a G202 here, it won't make any differece). Make sure your breaker is 50A or more on your 240VAC service. We're after real power.

Put on sunglasses or a welding helmet, stand way back and throw the switch. You are in for the ultimate nuclear detonation of a Geckodrive.
____________________________________

All these stories are true. We have over 60,000 drives out so everything and anything can and has happened. The earlier ones happen somewhat frequently. My personal favorites are the guy with the 12 drives and the 240VAC guy.

I wonder about the 12-drive guy. Why didn't he have clue something was wrong after the 2nd, 3rd, 4th, 5th,... 12th drive? I wonder about how many it would have taken; 20, 50, 100..? An excellent candidate for a QC tester in a match factory (yep, that one works, yep, that one works, etc).

On the hand, the 240VAC-guy wins for sheer brashness. He returned the drive for repair, stated outright what he had done and demanded a replacement for the 'DOA' drive. We sent him one. The returned 'DOA' drive was 2/3 gone. That means 2/3 totally missing. What was left was a puddle of molten aluminum and fiberglass cloth that weighed 1.5 oz out of the original 4 oz. The rest was simply gone.

The remains are behind a very tasteful glass display case in the office. It is by far the most destroyed Gecko ever on earth.

Mariss

[MikeAber]

I’ve been a communications electronics technician for over 35 years. I've seen all of these scenarios with my own eyes and more.

Even the "pros" can't seem to figure out that polarity to the $3,000 police or fire radio is reversed until 5 or more new radios have experienced meltdown mode and the 50A fuse was bypassed completely because the corporation yard installer had a box of "defective" fuses that keep blowing!

Why does the fuse blow and smoke come out when I plug the black and red power leads into the wall outlet?

How about 24 VDC to the 12 VDC radio systems, (very common) or what about bad radios that keep blowing up the D8 battery and all the lamps in the fire department's ladder truck because the charging system is charging the battery at 100V or more. (In this case the fire department needed to put the radio fire out.)

"Technician work is easy; just keep changing defective parts until you find a good one!"

It’s interesting how many “technicians” put a blown fuse back in the fuse holder and return the equipment for warranty repair after they’ve melted the PCB traces and vaporized the polarity protection diode but forget to put the original 3A fuse in the fuse holder instead of the 20 or 30A vaporized fuse. This is by far the most common warranty issue.

These warranty issues must be expedited! "What do you mean my new $1,000 portable radio isn't covered under warranty? The fact that it's full of water shouldn't make any difference!" What kind of junk are you guys selling anyway?

It's truly amazing what happens to electronic devices!

[PEU]

Mariss, one of the funniest posts I read in the year (and I read a lot) I also sold years ago 10 thousands of an electronic product and its unveleibable what people do to trash a perfectly fine product and then ask for warranty...

You should post it as a sticky in the gecko forum !!!


Pablo

[Apples]

Mariss, take a pic of the 240volt gecko and put it on here so we can have a look.

Peter
Australia

[2muchstuff]

Calculate for maximum smoke.

[Cncdemon]

Should I remove the back coating of the gecko drive to make for better heat transfer to a heat sink. Any thoughts? Using a heatsink with fan. Thanks

[[email protected]]

By saying this you will make warranty issue's "I know the Gecko specs state a maximum of 7amps so does this mean I have to lower the output of my P/S? If so how would this be done?
My stepper motors are rated for 48VDC @ 8.1Amps".
Your only option's are get a smaller motor within 201's specs or use a 5-6 amp fuse in line and hope to hell it blows out fast

[Mariss Freimanis]

Cncdemon,

The "coating" is mil-grade hard anodizing. Anodizing creates a ceramic material called aluminum oxide. Aluminum oxide is the third most heat conductive ceramic, right behind beryllium oxide and beryllium nitride. The oxide layer is 0.004" thick which means there is almost no temperature loss across it. It would be very difficult to remove it and pointless besides.

Mariss