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1
Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by mvs sarma on July 21, 2014, 07:27:54 AM »
Hi again :) There is the circuit in ".png" Format.
hi James Bond O ,
 you may have to indicate the  error image and  to members.
 Otherwise, getting some error message doesn't appear a good way of reporting.
 you can capture the screen and  upload as  .png.
 it helps  proteous gurus to study and comment.
2
Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by audioguru on July 20, 2014, 07:17:15 PM »
Your schematic looks fine. I do not know what error Proteus is giving but maybe it knows nothing about the opamps.
3
Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by OO7O on July 20, 2014, 05:02:39 PM »
Hi again :)

There is the circuit in ".png" Format.

4
Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by audioguru on July 19, 2014, 09:48:08 AM »
I Draw this circuit with PROTEUS-ISIS but cant simulate because a error, can someone help me to find the problem pls.
Very few people use your Proteus program. For us to see if there is something wrong with your schematic then please post it as a normal PNG file type that everybody can see.

Maybe you can "copy screen" then paste the schematic into a picture viewer like Paint program then save it as a PNG file type.
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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by OO7O on July 19, 2014, 04:32:24 AM »
Hi everyone.

I Draw this circuit with PROTEUS-ISIS but cant simulate because a error, can someone help me to find the problem pls.
6
Electronic Projects Design/Ideas / Re: Voltage Level Switch
« Last post by Hero999 on July 18, 2014, 06:00:56 PM »
A comparator & voltage reference IC will do this.

See links below for datasheets:
http://ww1.microchip.com/downloads/en/DeviceDoc/22269B.pdf
http://www.micrel.com/_PDF/mic841.pdf
7
Electronic Projects Design/Ideas / Voltage Level Switch
« Last post by dpaulovich on July 18, 2014, 05:10:05 PM »
I Have an aneometer that outputs 0-2 vdc. I want to monitor that voltage and alarm if the voltage falls below 1.5 vdc.
Does anybody have a circuit diagram with parts list?

Thanks 

Dan
8
General / Project Keebler house-piggybank
« Last post by atlanticav on July 13, 2014, 10:44:37 AM »
We had an unusual request this week. A customer came in with this keebler piggy bank and wanted led's inside and over the door with a motion sensor so that when you walk into the room the bank lights up. This was a cool project, and well we had a lot of fun. Thought I would share.



9
Power Electronics / turning my old arc welder into a mini spot welder
« Last post by flippityflop on July 13, 2014, 05:10:59 AM »
i'm trying to find more uses for my current arc welder which has the specs of
mode 1: 25V @ 50A and
mode 2: 23V @ 70A
(i forgot the cycles for each, but it's less than 60 secs or so)

so i figure i'd modify it to also function as a mini spot welder... i'm targeting about 1.5-3V @ 750A max

since my welder already ramps down the AC to above voltages, i figure it that there are other taps in the transformer that might go down pretty close to 3V.... well i opened the thing for the first time (and confirming my hunch that it's just one big transformer, as implied by it's low price 4 years ago), and found no other taps.

so i'm thinking maybe buy another large transformer core, say one taken from a microwave oven, rewind it's coil (and having the secondary a much thicker gauge), then connect it to my old welder; bringing 23 or 25V down to 1.5V.
but... i could've just connected the microwave oven transformer to the mains in the first place... like some diy-ers have done and blogged online.

so which is better, connecting the microwave salvaged transformer to the welder transformer first (2 stage) or directly to the mains??

would the other handle higher currents than the other configuration?
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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by audioguru on July 11, 2014, 12:22:08 PM »
hello audioguru! i am a newbie in electronics. i want to know that why the opamps like CA3140, CA3240 etc do not work at all in this circuit though they are capable of operating with single supply. i know they have a max operating voltage of only 36 volts but still if i require a low o/p voltage from the supply, the circuit does'nt work at all with these opamps.
The circuit might work with CA3140 opamps if the supply voltage is reduced by using a custom made 22V AC transformer but then the maximum output will be only about +22.5V DC at 3A if you are lucky. You might need to re-calculate a lower value many of its resistors so that the currents in the circuit are adequate. 
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