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Author Topic: 'Overclocked' soldering iron: Can a 50W iron withstand 70W?  (Read 2052 times)
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I bought an 80VA 24 volt transformer and ordered a 24V 50W soldering iron (big mistake). Since i would like to get as much power as possible from the transformer i thought of 'overclocking' the iron a bit. I was thinking of turning the AC output of the transformer into DC with the use of a bridge rectifier, and then set the ripple of the output waveform using capacitors. This way i would increase the voltage going to the iron and therefore its power output ( to lets say 70w). The iron's temperature will be monitored and kept constant.

My question is:
Would it be a good idea to 'overclock' the iron or will it get burned?

Thank you in advance
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I bought an 80VA 24 volt transformer and ordered a 24V 50W soldering iron (big mistake). Since i would like to get as much power as possible from the transformer i thought of 'overclocking' the iron a bit. I was thinking of turning the AC output of the transformer into DC with the use of a bridge rectifier, and then set the ripple of the output waveform using capacitors. This way i would increase the voltage going to the iron and therefore its power output ( to lets say 70w). The iron's temperature will be monitored and kept constant.

My question is:
Would it be a good idea to 'overclock' the iron or will it get burned?

Thank you in advance

I don't know why ordering a 80 watt transformer to drive a 50 watt iron is a 'big mistake', the iron will only draw the power it requires according to it's resistance. However if you can somehow raise the voltage output of the transformer you could force the iron to draw more power and deliver a higher temperature, unless it's of the temperature controlled type.

 The key specification of running a soldering iron is it's running temperature, too hot or too cold will make soldering more difficult. Different solder formulas have different optimum temperature ranges so that is a factor also.

 Bottom line is you should be more concerned about the temperature output of the iron, not the power consumed. What temp is your iron running presently? What temp do you wish it to run at? If you can't answer those questions then you have little to gain trying to force more or less power to your iron.

Lefty
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The iron is the hakko 907 which has an inbuilt temp sensor. The thing will be connected to an atmega which will pulse a mosfet (or triac)in order to keep the temperature of the iron constant under any condition (whether soldering IC pins or large components). A large transformer (80W) is a 'problem' since it takes up more space than a lower power one, which doesn't allow for a more compact unit. But since i got the power i thought why not deliver it to the iron (which would theoretically result in faster heating up times and a more responsive iron). My concern is that the heater of the iron will fail as a result of the extra power.
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The iron is the hakko 907 which has an inbuilt temp sensor. The thing will be connected to an atmega which will pulse a mosfet (or triac)in order to keep the temperature of the iron constant under any condition (whether soldering IC pins or large components). A large transformer (80W) is a 'problem' since it takes up more space than a lower power one, which doesn't allow for a more compact unit. But since i got the power i thought why not deliver it to the iron (which would theoretically result in faster heating up times and a more responsive iron). My concern is that the heater of the iron will fail as a result of the extra power.

Well short of raising the voltage output of the transformer there is nothing you can do at the soldering iron end to make it heat up any faster. And raising the voltage may damage the temperature control circitry of the iron. So all in all your fantasy is probably best left as a fantasy.

Lefty
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The circuitry is a K type thermocouple isolated from the 24 volts of the iron. If more power is forced through the iron by increasing the transformer voltage, wouldn't this mean more power dissipated at the iron and therefore a higher temperature rise in a shorter period of time?

 [t:temp, T:time, m:mass, c:specific heat capacity, E:energy, P:Power]   
   (E = mcΔt)      =>     E/T = mc*(Δt)/T   =>   P = mc*(Δt)/T

According to the equation above, a higher energy input per second will result in a higher temperature rise for a given time, since the mass of the iron and the specific heat capacity of its material are constants.
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The circuitry is a K type thermocouple isolated from the 24 volts of the iron. If more power is forced through the iron by increasing the transformer voltage, wouldn't this mean more power dissipated at the iron and therefore a higher temperature rise in a shorter period of time?

 [t:temp, T:time, m:mass, c:specific heat capacity, E:energy, P:Power]   
   (E = mcΔt)      =>     E/T = mc*(Δt)/T   =>   P = mc*(Δt)/T

According to the equation above, a higher energy input per second will result in a higher temperature rise for a given time, since the mass of the iron and the specific heat capacity of its material are constants.

I did say raising the transformer's output voltage would allow for faster heatup, but will the electronics in the soldering iron controller that reads that thermocouple and controls the power going to the iron be happy with a higher then designed voltage? Best stick to 'overclocking' PCs.

Lefty
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The atmega, opamps, display etc would't have any problem since they would be powered by a voltage regulator (probably a switching voltage regulator). My concern as i said before is the reliability of the heater of the iron under such conditions.
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The atmega, opamps, display etc would't have any problem since they would be powered by a voltage regulator (probably a switching voltage regulator). My concern as i said before is the reliability of the heater of the iron under such conditions.

Well do what you wish, but your kind of on your own. I have a Weller soldering station of probably the same wattage range and it heats up in maybe 10-15 seconds, so I would see no need to try and make it faster.

Lefty
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Thank you very much for your help mr.Lefty. Closed loop temperature controlled irons are okay but the real deal are the Metcal ones. The problem with those beasts is that they are quite expensive.
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Quote
My concern is that the heater of the iron will fail as a result of the extra power.

Wow,  for someone with a soldering iron,  your understanding of electricity is very poor.

A 24V transformer will present 24 volts at its output terminal, regardless of its rating.   The current flowing into the
resistive heating element of the soldering iron will depend on the input voltage applied to the soldering iron,  and it's
resistance.  The current and power consumed will be the same.   The bigger transformer won't "push" more power into
the soldering iron.
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You may also find that AC power is an essential requirement of the temperature control since it may contain a burst-fired thyristor.  If you feed it with DC power it may turn on and stay on.  Also your understanding of RMS in relation to AC heating effect is wanting.  50 watts is 50 watts whether it comes from AC or DC.  50VA assuming unity power factor is 50 watts.  Unless someone can advise otherwise  smiley
And the use of the term "over-clocked" is totally incorrect in the context of your enquiry - the term relates purely to clock-speed in microprocessing.
« Last Edit: March 10, 2013, 05:06:06 am by jackrae » Logged

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That reminds me of a project I did many years ago, when temperature-controlled soldering irons were very expensive. I decided to turn my 25W 240V uncontrolled iron into a temperature controlled one. I used a bridge rectifier and capacitor to increase the voltage, just as you are thinking of doing, and a thyristor on the input to control it. The heating element formed one leg of a bridge, which which fed some electronics (op amp and 555 timer I think), which controlled the thyristor.

Although I got it working, using the element itself as the temperature sensor didn't work very well. The problem was that the wire that the element was wound from turned out to have a very low temperature coefficient (much lower than typical metals), so the values and temperature stability of the other components were very critical.
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