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31  Using Arduino / Motors, Mechanics, and Power / Re: 'Overclocked' soldering iron: Can a 50W iron withstand 70W? on: March 08, 2013, 03:27:48 pm
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.
32  Using Arduino / Motors, Mechanics, and Power / Re: 'Overclocked' soldering iron: Can a 50W iron withstand 70W? on: March 08, 2013, 03:17:56 pm
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.
33  Using Arduino / Motors, Mechanics, and Power / Re: 'Overclocked' soldering iron: Can a 50W iron withstand 70W? on: March 08, 2013, 03:10:11 pm
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.
34  Using Arduino / Motors, Mechanics, and Power / Re: 'Overclocked' soldering iron: Can a 50W iron withstand 70W? on: March 08, 2013, 02:47:21 pm
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.
35  Using Arduino / Motors, Mechanics, and Power / 'Overclocked' soldering iron: Can a 50W iron withstand 70W? on: March 08, 2013, 02:27:07 pm
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
36  Using Arduino / Motors, Mechanics, and Power / Re: Soldering station : Use a TRIAC or MOSFET to drive the heater? on: February 23, 2013, 08:30:47 am
So what do you guys suggest that i use?
37  Using Arduino / Motors, Mechanics, and Power / Soldering station : Use a TRIAC or MOSFET to drive the heater? on: February 20, 2013, 04:16:30 pm
I was planning on building a homemade soldering station. Basically a 24 volt 60 watt soldering station handle (hakko 907) would be interfaced with an atmega 328. The integrated thermocouple of the handle will be read by the mega (through an opamp) and the heater of the handle will be accordingly switched on or off to keep the tip temperature constant to a preset value.

There are to ways that i am aware of in order to feed the heater with current:
A)Connect the secondary 24 volt 60 watt AC output of the power transformer in series with the heater via a triac and drive it with the mega using a triac driver.
B)Connect the secondary 24 volt 60 watt AC output of the power transformer in series with a bridge rectifier and the heater and drive the circuit using an N-channel enhancement MOSFET which will be directly interfaced with the mega.

>Which one of the two ways of driving the heater is the best?
>What are the advantages and disadvantages in each case?
>Is there any other better way to drive the heater?

All suggestions are very welcome.

Thank you in advance
Regards
 
38  Using Arduino / Motors, Mechanics, and Power / Re: How do NiCad and NiMh chargers detect -deltaV to stop charging? on: February 18, 2013, 11:19:00 am
I do indeed have a battery charger (Turnigy Accucel 6). I was asking this question because i did not know how it would charge NiCads or NiMhs using the -deltaV method and i was planning on using such technology to charge NiCads or NiMhs with a microcontroller. Thank you very much Retro for explaining what's basically inside the charger and thank you Lefty for answering the question.

Again, thanks both of you. This case is closed smiley
Have a nice day. Thanx.
39  Using Arduino / Motors, Mechanics, and Power / Re: How do NiCad and NiMh chargers detect -deltaV to stop charging? on: February 17, 2013, 03:33:32 pm
With that last clarification i think i understand what you are saying mr. Lefty. Please correct me if i am wrong:

You are basically saying that as the battery charges up, its voltage increases. A constant current charger will try to maintain a constant charging current and therefore will also increase its charging voltage more or less in the same manner as the battery itself increases its own voltage (since it charges up). When the battery is at full charge, its voltage (aka EMF) will start dropping. The charger will keep the charging current constant and will therefore have to decrease its battery charging voltage in a similar manner, following the voltage drop (-deltaV) of the battery. By measuring the drop in voltage of the constant current charger we can identify a drop in the voltage and therefore stop the charging process since the battery is full.

Am i correct?
40  Using Arduino / Motors, Mechanics, and Power / Re: How do NiCad and NiMh chargers detect -deltaV to stop charging? on: February 17, 2013, 12:46:18 pm
@ Mr.Lefty
I know for a fact that in order to charge a battery that has an open circuit voltage of lets say 6 volts, at any current, the voltage you supply to the battery (aka power supply voltage) has to be higher than the 6 volts of the battery. If you connect a voltmeter across a charging battery then you would essentially measure the voltage supplied to the battery by the charger in order for it to charge and not the actual EMF of the battery.

@ Mr.Retroplayer
Say i have a 9 volts supplied to the circuit you are suggesting. The voltage drop across the resistor is 1 volt and the current through it (and the battery etc) is 1 ampere. Then as you suggest the voltage across the battery would be 8 volts, and as Mr.Lefty said earlier, this could be simply done using a voltmeter across the battery, since i am not interested in the current going to the battery (there is no need for the shunt resistor). The voltage across the battery is the voltage provided by the charger to the battery and not the EMF of the battery. I want a way to measure the EMF of the battery, if there is one, other than disconnecting the battery and measuring the open circuit voltage.
41  Using Arduino / Motors, Mechanics, and Power / Re: How do NiCad and NiMh chargers detect -deltaV to stop charging? on: February 16, 2013, 06:57:19 am
What i am asking is how do the chargers to this. ie how can it be done with a microcontroller. I would like some technical details. I mean, the "loop" that the microcontroller would have to repeat in order to figure out when this -deltaV has been reached and some circuitry that would be required.

@Mr.Retroplayer:
You kind of confused me there. If i understood correctly, you are basically saying that by knowing the voltage you provide to the battery through the series resistor and the voltage drop across the resistor in series with the battery you can calculate the EMF of the battery ?? (ie EMF of the battery = voltage supplied to the resistor and battery - Voltage across the series resistor)
>Wouldn't this equation give me the voltage that is used to charge the battery?
>Would it give me the actual EMF of the battery in order for me to log the data down and be abple to determine the -deltaV?
> Wouldn't i have to stop the charging process, measure the open circuit voltage of the battery and the continue with the charging process in order to measure the EMF of the battery?
>By the way, i know that for lipos, its mostly the cell voltage that changes (drops) while the battery is drained (increase in internal resistance has a smaller effect). Does this not apply for NiCads and NiMhs? Does internal resistance vary greatly while the EMF of the battery remains more or less constant?

@Mr.Lefty:
How do you continuously monitor the battery terminal voltage while charging? What to you mean the change in direction of the voltage?

Again thanks for the help people.
42  Using Arduino / Motors, Mechanics, and Power / How do NiCad and NiMh chargers detect -deltaV to stop charging? (SOLVED) on: February 15, 2013, 01:29:40 pm
As you know, one way to detect whether a NiCad or a NiMh battery is fully charged is when the battery voltage starts dropping (-deltaV). My question is: How do chargers detect such a drop in voltage while the battery is charging? The only way to measure the battery voltage is to stop the charging process and measure the voltage right? How would a microcontroller be programmed to detect such a voltage drop? (ie charge for 2 mins, stop charge, measure voltage, store value, charge for 2 mins, stop charge, measure voltage, store value, compare the present value to the value obtained 2 mins ago)

Can someone please educate me on this matter?

Thanks in advance

43  Using Arduino / Motors, Mechanics, and Power / Re: Metal ring around motors--> FLUX RING (Question) (SOLVED) on: February 15, 2013, 01:07:50 pm
Thanks for the info Lefty smiley
44  Using Arduino / Motors, Mechanics, and Power / Re: Metal ring around motors--> FLUX RING (Question) (SOLVED) on: February 07, 2013, 01:25:22 pm
I just googled it and the search came up with results of a crazy scientist and the flux capacitor and time travel etc. It's a TV show right? I must have watched one or two episodes of the show a long time ago as i remembered his face but not enough shows for me to know the title of the show or to have witnessed the extraordinary/amazing power of the FLUX CAPACITOR :O
45  Using Arduino / Motors, Mechanics, and Power / Re: Metal ring around motors--> FLUX RING (Question) (SOLVED) on: February 07, 2013, 01:13:41 pm
And whats a flux capacitor? :O
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