Greetings: Welcome to the next phase of AAAWelder. I have enhanced the design and performance of my 70 Amp Arc Welder . I've clocked the mega buzz box welder in at an incredible 131 amps ac. Believe it or not, this revelation of "doubling the power" was the result of diagnosing a defective transformer The MOT: Modified . The mega buzzbox welder is designed from that principle but with it came a degree of responsibility, on my part as the builder, not to get greedy and kill myself in the process. I had to decide when enough was enough and be satisfied I took it safely to that point.
If you are new to AAAWelder, and need help gathering materials for the mega buzz box welder or preparing transformers, visit Build A 70 Amp Arc Welder .
I chose a retired CPU case to house the mega buzzbox welder, mainly because I have added quite a bit of hardware to this homemade welder. Here the case has been stripped and the first transformer installed. If you look closely, you will see that this is the transformer with the reduced ( defective ) primary coil.
This fan/bracket assembly was removed from a discarded microwave oven and installed in the CPU frame as a unit. This is one of those rare occasions when something actually goes in as planned. Don't get used to it!
The transformers are installed so that their magnetic fields don't interact with each other and cause adverse effects. I accomplished this by turning the plane of the transformer/coil center lines 90 degrees to one another.
I salvaged these 15 Ohm 1Watt resistors from an old marine transceiver. The two resistors will be ganged to produce a 30 Ohm 2W resistor.
This relay was also salvaged from the transceiver. It is the key component in the latch circuit.
The addition of capacitors to the primary circuit is probably the most significant improvement in the mega buzz box. Properly installed, the capacitors will correct the power factor and minimize tripped breakers.
Wiring the components together is a bit more complicated than the 70 Amp Arc Welder . I wire everything together temporarily to make sure the circuits perform as intended.
Due to the reduction in the number of turns in the primary winding, I had to have a means
of controlling the increase in power in the secondary. The idea is to replace the reactance
lost in the primary with a source that I can adjust to achieve the target amperage, in other words
a degree of control. I designed and built this variable reactor
(inductor). Its function is to choke the secondary current down to supply the amperage for the largest
electrode that I can safely burn with this welder.
The reactor, as it is displayed here, is wide open (no choke) allowing full power.
Another shot of the reactor in the full choke position, maximum reactance.
All of the components have been installed and wired and this unit is ready for the next phase: Testing.
The "sacrificial lamb" (high current test load) is my old stand-by, a plastic coffee can filled
with a loose coil of 18 awg stranded insulated wire and topped off with cool tap water. When welding
current passes through the wire, the cool tap water prevents the insulation from disintegrating
provided I only push the current through the wire for a few seconds maximum. That is enough time
to get a reading on my DVM and turn the power off.
As I stated in the intro, I clocked the output of this welder at 131 amps which is more than I
need to burn the E6013 1/8" electrode. I will use the reactor to choke the amperage down until
the rod burns smoothly without glowing red hot halfway through the welding job.
