6210 Group Buy, AGAIN

[logsquared]

For those that may be interested.... I built a 6850 clone 5 or 6 years ago. It is lacking the ACG and power limiter portions. I have the PCB artwork somewhere. It uses the hard to find LM12 power op amp. I also have several lm12's I may part with if someone needs them. I also have several cambridge amps that I cant remember the model number. They are basically card mount 6850's but operate on +- 15V only. So to get full speed a power opamp rated at +-30V would need to be added to the output. Very simple circuit with 4-6 caps and two regulators.

[mixedgas]

If I had the LM12s, Lanek could be up quick. I'll know this evening how many working LM12s I have on the boards. If Not, LM3886 works just fine with some adaptation. I have another chip that works as well.

Steve

[logsquared]

Here are some on eBay. http://www.ebay.com/itm/New-Old-Stoc...item337fde9efc

Someone might wanna snatch em up!

I think I have 5 plus the one that is soldered on my 6850 clone.

[mixedgas]

MOPHEAD, Per your agreement with Jon, You have two amps ready to go, from the DSLI jon pile. I swapped out a few bad op-amps, tossed in a 7815, and hooked up my test bench sacrificial 6810 and tuned up the damping on a square wave. So they past the bench test! When troubleshooting amps I skip the patterns and do it per the Cambridge manual, using a signal generator, oscilloscope, and voltmeter. I'll need to set the scale factor for you before they ship. (See my PM)

The other five amps from DSLI Jon need LM12s or another type of new output stage such as a TDA24xx series and some other minor work. I'm waiting to hear from him about what I'm allowed to do with them. Lanek badly wants two boards.

I'm inclined to make my own boards for the rest of my galvo collection. So I'm not going to hang onto these.

I fixed my personal 6850 amps as well. Next weekend I'll have more time. I'll run a test pattern through the 6810s for grins and giggles. I'm out of town this week for work.

6810s need to be well heatsinked. With a low wattage +/- 24V supply and the Group Buy 6810-510P with the included mirror, I had no problems obtaining critical damping on the stock 6850 with no mods. There is about a turn and a half left on the potentiometer. I could change the gain resistor and get more reserve. I might play with that once I get a test pattern up.

Steve

[dsli_jon]

...I'm waiting to hear from him about what I'm allowed to do with them. Lanek badly wants two boards.

..They were, from the get-go, for whomever needs them.. I need nothing in-return.. (..though, sure - bottles of Patron are always welcomed.. So, hook Mr C, and whomever-else ya need to-up...

..Ok, caviat: If you get a million-dollars for the last-pair, I want a 1984 911 Carrera SC Turbo, in black, silver rims, leather, Alpine F1 and a Pictor 25 RYGB all-OPSL, deal? Short of that, you guys have fun..

ciao
j

[mophead]

Thanks all y'all. It is appreciated.

mop

[Bradfo69]

Here are some on eBay. http://www.ebay.com/itm/New-Old-Stoc...item337fde9efc

Someone might wanna snatch em up!

So... since I have these two galvo motors sitting here (and bought a scanner block) and no amps - and no idea how to build them - should I jump on this and buy a couple of these LM12's since they're supposed to be getting harder to find?? I'm assuming some helpful member will assist in the creation of amps somewhere down the line and, at least that way, I have the rare parts. How many do I need? 1 for each?

Signed,
"Clueless in Delaware"

[Bradfo69]

And... while we're on the subject, how about the ribbon cables that go between the motors and the amps?

[mixedgas]

I have a two dollar and fifty cent TDA part that will replace the LM12. The problem is its in a different package and will need a different heatsink. Some means to adapt between a T03 can and a T0220 5 pin. I bought a few but I need to try them.


The Ribbon connector to DB9 cable is made of inexpensive Digikey parts, and costs a few dollars to make. The tool used to crimp the connectors can be a bench vise.

And Brad, I just shipped you a box o' stuff.

Steve

[logsquared]

Steve,

Just put the LM12 in and forget about it. I checked. I have 5 and ebay seller above has 4. A collaboration on a clone may be design time better spent?