Voltlog #207 - Making a DIY Spot Welder From A Microwave Transformer

Comments · 190

• TH

  @Thermaliser · 5 years ago (edited)

  With a 35mm² AWG 2 wire, with 2 turns in secondary coil, I got 1.6v 522.4 A in my tip heads which are made of zirconium copper alloy. This alloy is the nessecary one to use in point welding machine cause of it&apos;s thermal resistance and conductance properties. I also use the 220v fan motor of the original microwave oven for cooling and one thermal fuse of the same oven and there is no heat problem so far. Fast and easy project.<br>For technical calculations of anyone interesting have in mind.. <br>How to calculate the output ampers? Use the equation : <br>Is = Vp/Vs • Ip<br>were Is = Amper of the secondary<br> &nbsp; &nbsp; &nbsp; &nbsp; Vp = Voltage of the primary<br> &nbsp; &nbsp; &nbsp; &nbsp; Vs = Voltage of the secondary<br> &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Ip = Amper of the primary<br>Now how to know the primary coil amperage is simple. Just devide your transformer given Watt number by the used voltage <br>e. g. 850/220 = 3.8A <br>(or for USA 750/120 = 6.25A) <br>Also if you are curious about how to count the primary turns for other calculations the equation is:<br>Vp/Vs = Np/Ns<br>were Ns = turns of the secondary and<br> &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Np = turns of the primary<br>So following this equation you can for example find that the primary coil turns of your transformer is:<br>Vp/Vs = 220/1.6 = 137.5 and for the primary turns you have to find the same number. So Np/Ns must be also 137.5 and that means <br>Np/2 = 137.5 &nbsp;so on Np = 2 • 137.5 = 275 turns on primary. <br>To ensure the calculations correctings just use the following equation:<br>Vp • Ip = Vs • Is this means<br>220 • 3.8 = 1.6 • 522, 4 (approximately) <br>is giving the same number. Correct!! <br>Hope I help some interested. Have fun with your project and always take a really good care of the current for your safety!

  21

• JA

  @jamest.5001 · 7 years ago

  I have been looking for a explanation of the way these boards work! Thank-you!

  3

• JA

  @jameswyatt1304 · 5 years ago (edited)

  Skip the hardware store for thick transformer wire and get a starter cable from an auto parts store.<br>Also, put thermal fuse on primary since the secondary current can weld it &quot;on&quot;...

  8

• JS

  @jstro-hobbytech · 4 years ago

  Cool build but I&apos;d go with a tact switch instead of a pedal to lower the storage footprint haha. I love seeing how different everyone breaks out the probes

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• DE

  @demoking1422 · 5 years ago

  Great work on the welder and explanation of your design , today is the first time I have seen your videos and they are great ! like your other viewers have stated we don&apos;t need music sound effects or how to get it out of the box just the facts very often over my head when it comes to the technicals in the electronic components but it gives me great confidence to know all that stuff is in there haha, Thanks !

  2

• LO

  @lovepreetsinghgill517 · 6 years ago

  I think this is best video on spot welder topic.

• OZ

  @ozisnice · 7 years ago

  Great job!

• AL

  @allmor77 · 7 years ago

  hey ,i have to spot welders for battery tab welding,one is build around an MOT with a Crouzet syr line digital timer (the timer was gift from my father-in-law,cause it&apos;s very expensive for a diy project cost around 200 euro) a solid state relay to switch the primary,the second welder is build around 8 irf1404 power mosfets an arduino timer &nbsp;and i&apos;m using it with a 450 CCA 12v car battery ,both of the welders working very well , i&apos;m planning to do a video for both of them &nbsp;with a more detailed presentation and explanation

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• HA

  @hardhatlifebrand · 7 years ago

  nice!! &nbsp;💪 👷🏻

• MA

  @Mars5826 · 5 years ago

  excellent video i was hoping to power it up- with a battery pack now i know why i can&apos;t thank you

• MU

  @muhammadnaveed6837 · 5 years ago

  I only say u r a great person.

• MC

  @MCsCreations · 7 years ago

  Really nice work, dude!!!