Hilo90mhz

use WIN VNC, its a free program that lets you remotely controll the computer just like you were at the desktop.. Through a TCP/IP network.

Hey.. ya, sorry about that, i got my decimal places mixed up ;D Im actually using 5.1v 1W zeners, with a regular diode in series, using the foreward voltage drop to bring it up to about 5.6v.. I have a 20mhz DSO, I dont think they are so slow that the peak is missed.. the sine just gets a flat top. My C1 is 10,000 uf.. I like the lightbulb current regulation just because its sooo simple.. nothing impressive about its performance. -- still waiting on the HV OP amps.. Chester

Thanks for spoting the error Audioguru!, I thought that connection looked funny.. but didn't bother to check it against the original schematic.. The bridge rectifier is a junkbox model CM3501 = 35A 100V It has a nice aluminum case for bolting to a heatsink, measured at .436 volt drop per diode Did you read my reply wrong? or am I missing something?, I was only getting 5 thousandths of a volt difference from no load to 1.2A load. Which could have by the leads going from the regulator output to my load... ( I was measuring on the load, not the regulator output) I did notice the bulbs almost constant current draw over different voltages.. makes a nice test load in that respect... must be the simplest constant current device there is. Ive fixed the V+ connection for U1 and the current regulation works great now.. I dont know what the best way to measure ripple on the output is.. My fluke multimeter reads zero AC voltage on the output, with or without a 1.2A load.

I think its doable.. but tons of work involved in firmware/circuit design. I have a friend who is building a 3 phase motor controller for an electric car.. He started about the same time I did on my 3 phase inverter, and neither of us are finished yet... (started april 2003) but of course not working on the project constantly... Most of the work is in firmware design.... the hardware is the easy part. Chester

Did you check for a DC-DC converter inside that wireless MIC ? most circuits that run off a single cell use a small DC-DC converter to up the voltage to a more reasonable 3.3v or 5v. Maxim IC makes some really simple dc-dc converter chips, with only a few external components needed. Ive used the MAX1674 before. If you want to have a working prototype in a week or two, you should probably find a finished design instead of starting from scratch.. A 555 timer is good for about 1mhz max, depending on which model, I think most of them only go to 500khz.. Prebuilt transmitter/reciever modules are really a bargain.. and let you spend more time on the rest of the circuit. Chester

Wound the transformer, etched and assembled the PCB, scrounged for resistors.. Just got it working a few minutes ago... The transformer puts out 26.06V AC unloaded and 25.78V AC loaded with 1.2A (on output of regulator) After the rectifiers = 35.16v DC unloaded and 33.47v loaded with 1.2A Regulator puts out 28.99V DC unloaded, 28.95v with a 1.2A load. The 1.2A load is just a halogen bulb I happened to have handy... Soon ill find a better load to test the full capacity, also this was just a test setup... its not in a case or anything yet, and im only using one 2n3055 right now. Ive ordered samples of the OPA445.. Ive noticed that the current limit just acts like a cutoff switch.. Id assumed it would just lower the voltage to that current, but it seems more like full off full on type of thing.. maybe its just really sensitive? Is this how most variable current PS work? The current limit is just like a cutoff? so you just use the voltage knob to do both? I can see it might be more usefull this way, especially if you have no voltage meters, because the output is either at the set voltage, or its at close to zero and the current limit LED is lit. I really appreciate all the time you guys have spent revising and improving this circuit.. All the hard work already done ;) Chester

Thanks for all the help everyone :) Thanks, I really need it... trying to switch 350Amps at 48v average is no joke yup, I discovered that by comparing pinouts.. and designed my PCB accordingly. Good point.. I assumed I could do some stress testing after it was completed and if it works it works... but youre right, if im running this close to the maximum limits... anything could happen. Id still like to try :P Maybe ill do some destructive testing on the OP177 to see just how high they will go, anyone for leaving this PS on for 4 days at a time? and then subjecting it to pulsed inductive loads... or something like that. I actually plan to build two of these supplies.. Using the same transformer core, but I wont build the second until I have the first working reliably, and maybe a fixed 12V and 5V supply also... who knows. Chester

Hello everyone :) Im in the process of building this PS.. Using the updated SMARTER kit schematic posted in this thread... I know there has been tons of talk about using higher voltage OP amps and issues with under rated transformers.. Ive read both threads about 1.5 times... - alot of info to digest Im building this with parts on hand.. which happen to be very close to those specified in the schematic. My OPamps are 44v OP177 types... now believe me I know they should be rated for more, but im stubborn and want to try with these for now.. if they start smoking ill try something else ;) Now because im trying to get about 5A... basically the most I can (the actual output will be measured later). I know this entitles using a higher voltage rated transformer, because of all the drops incurred along the way.. I also know that lower VA transformers have bad voltage regulation.. and would float at a much higher voltage when not loaded. So Im rewinding a microwave oven transformer.. Rated at about 600 - 800 W im guessing (still have to get out the scale to weigh all that iron). Ive removed the secondary and the primary looks real nice. Im going to determine the V/T ratio tomorrow with the original primary. My first question is: What do you think a good unloaded secondary voltage would be? I think 26V AC is the max I can go and stilll keep below the 44v DC OP amp limit, because 26v * 1.5(because of AC RMS to near peak conversion)= 39v +5v(for - supply) = 44v ( ignore the extra .6v or else its over= I like to live dangerously ; ) Will 26v AC unloaded be enough to deliver 30v DC loaded on the output? Keep in mind the transformer core is rated for about 600W I will be able to change the secondary turns/voltage without too much trouble later on... I just want a good starting point. Thanks, Chester Lowrey http://www.hot-streamer.com/hilo90mhz/