From your comments and my thoughts, I doubted my readings, so I repeated them. Oooops! Sorry

I tried the thermocouple my test again, and found it does give off mV.

That makes much more sense given the rather low resistances seen in previous examinations

I hate to 'do this' to you -- Might I prevail upon you to repeat the procedure but for current measurements?

Best regards
HP

 

As i said earlier, tip is the heater, ring is thermocouple.

How many more tests do you need..?

 

As i said earlier, tip is the heater, ring is thermocouple.

How many more tests do you need..?

It certainly looks that way -- But let's be sure -- if he applies current to the wrong leads - poof goes the TC!

Best regards
HP

 

It certainly looks that way -- But let's be sure -- if he applies current to the wrong leads - poof goes the TC!

Best regards
HP

HP,

I agree with you and DD, too, but at £38 I don't mind being a bit patient. Also I have another larger similar iron, so what I'm learning will help me with that one too. (I have already popped one of them )

I was getting unclear readings from 3x digital meters, so I averaged the readings (They may not be accurate). I assume CURRENT = Ohms??

Here are resistance readings.
COLD
GND to RING 4 Ohms
GND to TIP 4 Ohms
REV
RING to GND 2 Ohms
TIP to GND 4 Ohms

HOT
GND to RING 16 Ohms
GND to TIP 2.5 Ohms
REV
RING to GND 12 Ohms
TIP to GND 6 Ohms

Hope that all

C.

 

I assume CURRENT = Ohms??

Incorrect -- The unit of electrical current is the Ampere (Amp) -- For these purposes you'll be reading low mA (milliamperes)...

As an aside -- In case you may find it useful, I offer the following table of common electrical quantities often measurable with basic test equipment -- Please note that the following is unsorted but loosely grouped by 'association' in test application...

Electrical Quantity ---------- Integral units
Current.....................................Amperes
EMF..........................................Volts
Resistance/Reactance/Impedance..Ohms
Power.......................................Watts
Apparent "power"........................Volt Amperes (Note: caveats apply!)

Capacitance...............................Farads
Inductance................................Henries (Occasionally 'Henrys')
Q (Quality Factor).......................No unit 'quantity' is a factor
D (Dissipation Factor)..................No Unit 'quantity' is a factor (Note: Informal)
Frequency.................................Hertz (1 Hertz=2∏ radians per second)

Very best regards
HP

 

Addendum -- Attn: @camerart --- Please read!

While my advice offered in post #41 is sound -- It occurs to me that it may have left you with a dangeriously wrong impression as regards proper use of an 'invasive' current indicator!

Generally speaking it is neither 'standard' nor advisable to shunt a source of electrical energy with a current indicator! --- My suggestion in post #41 is viable owing to the fact that thermocouple output EMF is sufficiently small such that the internal resistances of the test apparatus and the effective resistance of the thermocouple itself will limit current to a safe level --- In general use - good safety practice will regard an invasive current indicator as presenting zero impedance and the PSU as capable of infinite current --- hence invasive current measurement will properly be in series with an impedance!

Again, you may confidently heed the suggestion of post #41 -- but please do not regard same as descriptive of typical use of a current indicator!!! --- Should you have any questions please don't hesitate to ask!

Best regards
HP

 

HP if there is phobia for worried that you're misunderstood then it's you! I think fitting epitaph will be _HP The Disclaimer_

Camerart soldering station only overpriced because what market will bear! Even if HP right that you can get it half price still overpriced I say kudos for experiment with parts and design your own instead of playing their game and paying their price like obedient lamb! So I give you all likes cuz it is rare ppl like you who keep marketeers in check!

 

Hi HP,

Thanks for your care in replying. I have days of confidence and a box of 'popped' items to prove it I also have days of dyslexia, where a RED lead is black so more items for the 'popped' box

Just burnt myself on a fast heating soldering iron. GND to TIP is the heater. I connected 12v and it was hot in no time.

Just before connecting, I had a moment of logic. Remember the bit has a Jack socket for connection, so if the bit was changed while still on, the heater element wouldn't connect till it was completely into the jack socket.

Now I need to investigate a Thermocouple resistance to PWM circuit

Thanks for your help.

C.

Addendum -- Attn: @camerart --- Please read!

While my advice offered in post #41 is sound -- It occurs to me that it may have left you with a dangeriously wrong impression as regards proper use of an 'invasive' current indicator!

Generally speaking it is neither 'standard' nor advisable to shunt a source of electrical energy with a current indicator! --- My suggestion in post #41 is viable owing to the fact that thermocouple output EMF is sufficiently small such that the internal resistances of the test apparatus and the effective resistance of the thermocouple itself will limit current to a safe level --- In general use - good safety practice will regard an invasive current indicator as presenting zero impedance and the PSU as capable of infinite current --- hence invasive current measurement will properly be in series with an impedance!

Again, you may confidently heed the suggestion of post #41 -- but please do not regard same as descriptive of typical use of a current indicator!!! --- Should you have any questions please don't hesitate to ask!

Best regards
HP

 

Thanks to all. HAPPY SLODERING

EDIT: Just found the 'edit title' button

Camerart.

 

@camerart
Pleased to learn common sense prevailed (for a change)!

Now I need to investigate a Thermocouple resistance to PWM circuit

Recall that a thermocouple is an EMF (i.e. 'Voltage') source -- From a conceptual standpoint, a temp control system may readily be implemented via a 'servo loop' comprised of a differential amplifier featuring a 'variably scaled' reference EMF at its non-inverting input, the conditioned thermocouple 'signal' at its inverting input and development of the PWM control signal following its output... If you don't wish to 'wade through' design of compensation/'loop filter' networks - I can but assume the 'web' is replete with time tested circuit examples...

Best regards and best of luck!
HP

 

Or alternatively use an AD595 chip ready-made for JK type thermocouples, i do...

 

Or alternatively use an AD595 chip ready-made for JK type thermocouples, i do...

Sounds like a plan! -- Reinvention of the wheel is for masochists and those ignorant of what's available in the way of integrated solutions (pointing finger directly at self)

Best regards
HP

 

Or alternatively use an AD595 chip ready-made for JK type thermocouples, i do...

Hi DD,

The cheapest AD595 at Farnell is £10 and 3Deg tolerance.

I'm used to PICs with A to D converter and have a pile of them. I'll most likely try these first.

Thanks,

C.

 

Sounds like a plan! -- Reinvention of the wheel is for masochists and those ignorant of what's available in the way of integrated solutions (pointing finger directly at self)

Best regards
HP

Hi HP,

I'm going to start another thread 'Soldering station circuit' and see what others have done.

Me too! I start playing around with an idea, and after struggling for a long time, find it has already been done

When I was surprised (burnt finger) by the speed the iron heated up, at 12v. I guessed that it would heat up with less voltage. At 4V it melted solder in seconds, so 12v would most probably have burnt it out. Considering it runs from 24v it will have to be a fast control circuit.

C.