jjwwjj@mixcom.COM (Robotic Systems) (05/24/91)
After much praise in several newsgroups, I purchased a M68HC11EVB. Now I need a power supply! Any suggestions? I purchased a model PS-60 from ALL ELECTRONICS, but it doesn't seem to work properly. I am sending it back tomorrow. It makes clicking sounds when I connect 115VAC. Could be a short, but where? Anyway, I need a power supply: INPUT 115VAC, OUTPUT +5VDC @ 0.5A, +12VDC @ 0.1A, and -12VDC @ 0.1A. A PC power supply should work fine. Does anyone have a used power supply? I need one fast and cheap. Thanks. -- =============================================================================== Clint Laskowski Post Office Box 552, Cudahy, Wisconsin 53110-0552 ROBOTIC SYSTEMS INTERNET: robots@mixcom.com VOICE: (414) 769-9332 ===============================================================================
bcc@Eyring.COM (Brian Cooper) (05/28/91)
In article <823@mixcom.COM> jjwwjj@mixcom.COM (Robotic Systems) writes: > >After much praise in several newsgroups, I purchased a M68HC11EVB. Now >I need a power supply! Any suggestions? > >Anyway, I need a power supply: INPUT 115VAC, OUTPUT +5VDC @ 0.5A, >+12VDC @ 0.1A, and -12VDC @ 0.1A. A PC power supply should work fine. > I found myself in the same fix when I got my EVB. Radio Shack doesn't have anything like what I needed, so I went to the local Deseret Industries (translate to Salvation Army/Thrift Shop/Harry's Pawn Shop/Bob's Army-Navy) where I bought a TI 99/4A for $6. The internal power supply (make sure you get the transformer that goes with it) supplies +5/+12/-5. I worried about the -5 not being -12 but it is only used for the RS 232 and just looks to the other system like a long cable has attenuated the signal. Works fine!
bame@hpfcbig.SDE.HP.COM (Paul Bame) (05/29/91)
> After much praise in several newsgroups, I purchased a M68HC11EVB. Now > I need a power supply! Any suggestions? > Anyway, I need a power supply: INPUT 115VAC, OUTPUT +5VDC @ 0.5A, > +12VDC @ 0.1A, and -12VDC @ 0.1A. A PC power supply should work fine. > Does anyone have a used power supply? I need one fast and cheap. Relax that -12VDC requirement a bit (it's for the RS232) - like to -5VDC and you can use the widely-available surplus wall-cube supplies made for Coleco Adam (or or Commodore something) [+12 +5 -5]. Sometimes they are available at Rat-Shack and they are often available from someone in Radio-Electronics. I bot one in Denver ($6.95 - one dollar too much) at Gateway Electronics and my EVB is happy. Probably not guaranteed to work with all serial ports everywhere but the price is right. It's almost worth hacking the board to use a MAX233 and run on +5 only. -Paul Bame bame@hubble.sde.hp.com N0KCL
kline@ux1.cso.uiuc.edu (Charley Kline) (05/29/91)
In article <823@mixcom.COM> jjwwjj@mixcom.COM (Robotic Systems) writes: >After much praise in several newsgroups, I purchased a M68HC11EVB. Now >I need a power supply! Any suggestions? > >Anyway, I need a power supply: INPUT 115VAC, OUTPUT +5VDC @ 0.5A, >+12VDC @ 0.1A, and -12VDC @ 0.1A. A PC power supply should work fine. The only thing the HC11EVB uses +12 and -12 for is the RS232 line drivers and receivers. These are socketed chips; if you pop them out and replace them with a MAX232 (or other similar charge-pump-based RS232 driver), you will not need the higher voltage supplies at all. The EE department here builds little circuit boards with plugs on the bottom to plug into the 1488 and 1489 sockets on the EVB and the circuitry on top to do the RS232 driving stuff. Pretty slick. The EVB is nice, too; I managed to get the assembler to work on my Mac even though the documentation says it won't work on a Mac II and won't work on an HFS file system. I've had a couple of projects cooking for a while that I abandoned because of complexity; now I can effectively replace large quantities of circuitry with a box labeled "6811". I'd like to start some prototyping discussions here, maybe. While we're on the subject of 6811's, which of the various varieties have people seen available quantity-one? I'm mostly curious about the '711 EPROM variants. Looking at Motorola's repertoire of 68HC11 derivatives, I can imagine the prices for them would vary widely. ________________________________________________________________________ Charley Kline, KB9FFK, PP-ASEL c-kline@uiuc.edu University of Illinois Computing Services Packet: kb9ffk@w9yh 1304 W. Springfield Ave, Urbana IL 61801 (217) 333-3339
kline@ux1.cso.uiuc.edu (Charley Kline) (05/29/91)
I wrote: >In article <823@mixcom.COM> jjwwjj@mixcom.COM (Robotic Systems) writes: >The only thing the HC11EVB uses +12 and -12 for is the RS232 line drivers >and receivers. These are socketed chips; if you pop them out and replace >them with a MAX232 (or other similar charge-pump-based RS232 driver), you >will not need the higher voltage supplies at all. WHOA! Upon re-reading my posting, I realize I gave the incorrect impression that the MAX232 is pin-compatible with the 1488 and 1489. IT IS NOT!! You'll have to do more than just replace chips to pull off this stunt. The MAX232 also requires kinda big external capacitors to run the charge pump. Sorry for any confusion. Hope no one fried their EVB after racing right home and trying out my bad advice. Also upon re-reading this thread, another poster suggested that a PC supply would work for this board. Maybe, but do keep in mind that the 68HC11 is a low-power device; the entire EVB only draws a fraction of an amp. Switching supplies like those in a PC (and perhaps the "clicking" supply also mentioned--switchers tend to make odd noises) do not regulate well at low load and in general, make bad bench supplies. I thought I had it made when I pulled a VAX-11 memory power supply out of the trash. 5 volts at FIFTY AMPS! Unfortunately, unless I boiled some water with a nice fat resistor to draw at least three amps (or so) from the monster, the five volt regulated output sulked at less than a volt. Great for a 1979 computer, not so good for me piddling around on my workbench. ________________________________________________________________________ Charley Kline, KB9FFK, PP-ASEL c-kline@uiuc.edu University of Illinois Computing Services Packet: kb9ffk@w9yh 1304 W. Springfield Ave, Urbana IL 61801 (217) 333-3339