| > The Harbor Freight website has links to manuals for many products, but | > I could find no link for the infamous 91811 welder. Unfortunately, I'm | > a few hours drive away from a retail store, so that option is out. By | > looking at the site location for the other manuals, I was able to | > determine the link to this welder. Here it is: | >
| > It looks like they just forgot to link to it on the product web page. | >
| > Glenn, you are right, there really is not much information in the | > manual. I sure am glad I didn't take up one helpful guy's offer to | > mail out a copy if I sent him $25!!!
Thanks for finding that for me! I was asking about it the other day to see what it would take to make it do more tricks, and to see if the schematic would allow it. What a pleasant surprise. I learned a couple interesting things. First, it rectifies the high
220V input (and lower current) then creates AC out of again it to drive the output transformer. After the transformer, it's rectified to DC. To pull AC out of it, it seems (to me, who knows so little!) that you could leave the DC part alone since it's used for feedback (I assume) and just add two terminals for the AC right out of the transformer, before the diodes. The diagram doesn't say what goes on inside the circuit board, but it seems reasonable that you could rig up a way to add variable frequency. I was thinking that you could drive a electronic potentiometer with a chopper circuit or oscillator to trick it into thinking HF, but I'm sure there's some filtering there, so I don't know how that would work, but it's an idea. The on-board oscillator that creates the frequency that drives the IGBT's that drive the output transformer might be modifiable, but reverse engineering would definitely be in order. Would be a fun project to see how little you can spend to make a $220 welder do tricks of more expensive ones. I'm just gonna have to budget some money when the wife isn't looking and play around with it myself. Hmmmm..... I got rid of a lot of my electronics stash, but not most of the good stuff..... Where the hell did I put my scope? Where do I put this on my to do list??
Slams, criticisms, or compliments? Anyone wanna contribute to my project fund?