Soldering Station: Transformer or Digital?

[DW1961]

I have a couple of cheap knock off stations from Amazon. Both of them use a huge transformer instead of digital. I heard a guy on Youtube tearing a couple of the cheap stations down and said he preferred the nice, large heavy transformers to the digital type. He said there is just less going on in the transformer type, and he liked that. He didn't elaborate.

So, what's the difference?

[Shock]

Transformers for utmost reliability, safety, esd safety, low noise design and parts count. They have a bit of weight and size to them and this is beneficial when using controls, connecting the handpiece or prevent it falling off the shelf.

Switching power supplies (smps) would be better suited for portability, lightweight or a high frequency station. There are also transformerless temp adjustable stations that are direct mains powered, most of these are dirt cheap and best avoided.

[DW1961]

Transformers for utmost reliability, safety, esd safety, low noise design and parts count. They have a bit of weight and size to them and this is beneficial when using controls, connecting the handpiece or prevent it falling off the shelf.

Switching power supplies (smps) would be better suited for portability, lightweight or a high frequency station. There are also transformerless temp adjustable stations that are direct mains powered, most of these are dirt cheap and best avoided.

Good information. Thank you.

I'm assuming that the transformer type would be more expensive also?

[Shock]

I don't think savings are passed onto the customers based on cost alone. Both transformer stations the Hakko FX951 is probably double the cost of the Hakko FX888D but has been sold at almost four times the cost in the past. So there are other things like technology, cost recovery, price protection and markup that makes some significantly more expensive than others.

Transformers are generally more expensive to manufacture, but as both transformers and smps can vary widely in quality, it would be a case by case basis.

[wraper]

SMPS has nothing to do with being digital. Unless it's a rare high performance type with microprocessor controlled switching. Also as long as iron is grounded, it does not really matter.

[DW1961]

SMPS has nothing to do with being digital. Unless it's a rare high performance type with microprocessor controlled switching. Also as long as iron is grounded, it does not really matter.

What about for simplicity sake, which means less electronics to go bad?

[james_s]

It really doesn't matter. If you get a decent quality unit from a reputable manufacture it will be dependable, the underlying technology is not important.

[Datman]

A 50Hz transformer solder supply will be useful for your children and for the children of your children; a switching one will not have a so long life

[S. Petrukhin]

There is no difference if you use a 3-core power wire including PE.
If the connection is without a ground wire, which is not uncommon in the household network, the switching power supply unit can transmit potential through the Y-capacitor because it can be on the phase wire.

[wraper]

A 50Hz transformer solder supply will be useful for your children and for the children of your children; a switching one will not have a so long life

If the rest of the circuit lasts as much. Also cheap transformers often overheat and trigger internal thermal fuse. Transformers are less robust against prolonged overvoltage of medium severity unless wound with significant headroom, and do not accept wide range of input voltages. SMPS more often than not can work in 100-240VAC nominal range just fine + some headroom.

[DW1961]

A 50Hz transformer solder supply will be useful for your children and for the children of your children; a switching one will not have a so long life

If the rest of the circuit lasts as much. Also cheap transformers often overheat and trigger internal thermal fuse. Transformers are less robust against prolonged overvoltage of medium severity unless wound with significant headroom, and do not accept wide range of input voltages. SMPS more often than not can work in 100-240VAC nominal range just fine + some headroom.

Not too worried about over voltage in my area. I live in the USA. Household voltage here is extremely well regulated.

[tooki]

A 50Hz transformer solder supply will be useful for your children and for the children of your children; a switching one will not have a so long life

If the rest of the circuit lasts as much. Also cheap transformers often overheat and trigger internal thermal fuse. Transformers are less robust against prolonged overvoltage of medium severity unless wound with significant headroom, and do not accept wide range of input voltages. SMPS more often than not can work in 100-240VAC nominal range just fine + some headroom.

Not too worried about over voltage in my area. I live in the USA. Household voltage here is extremely well regulated.

Not particularly, it's 120V +6/-13% in USA. Europe, for example, is 230V +10/-6%. Anecdotally, power quality in USA is far, far worse than in much of Europe, thanks to USA using lots of overhead lines that are more susceptible to issues. When I lived in USA, in a fairly decent place in one of the wealthiest states, I still chose to have a UPS to protect against blackouts and brownouts. I plain and simply do not have those issues here in Switzerland, for example. It's my understanding that from a worldwide electricians' perspective, USA is neither particularly bad nor particularly good, but definitely worse than what people expect from a highly-developed country.

Of course, with modern SMPSs, the entire US voltage range is thoroughly covered by the 90-250V (100-240V nominal) range of typical universal-input supplies, thanks to Japan's 100V nominal providing a generous buffer downwards, and all the 230V and 240V countries providing a huge buffer upwards. But it's interesting to look at, for example, test gear with transformer supplies, many of which provide a voltage selector for 100/120/220/240V, rather than just 120/230V like a lot of stuff.

[mariush]

To me digital  when it comes to soldering stations is using a microcontroller or some logic chip to control the temperature of the tip ...

an analogue soldering station (like Hakko 936 for example) uses a triac, an opamp and a regular potentiometer to adjust the temperature of the tip
 
a digital soldering station would use a microcontroller to read the temperature from soldering iron tip and 2-5 buttons where some buttons may be temperature "presets"... some stations are branded digital just for having a temperature readout on a lcd display.

I have two soldering stations, a genuine hakko 936 and a pace hw50, both with transformers... i like the weight, makes them harder to move around on the desk.

[tooki]

I have a couple of cheap knock off stations from Amazon. Both of them use a huge transformer instead of digital. I heard a guy on Youtube tearing a couple of the cheap stations down and said he preferred the nice, large heavy transformers to the digital type. He said there is just less going on in the transformer type, and he liked that. He didn't elaborate.

So, what's the difference?

Just to reiterate, digital vs analog has nothing to do with the power supply type. Most digital soldering stations use transformers. And though I haven't seen one, it'd certainly be possible to build an analog soldering station using an SMPS.

SPMSs are rare in soldering stations, perhaps because of the leakage voltage on the outputs if the device isn't grounded properly. (The EMI reduction class-Y caps overlay about 1/2 the mains voltage onto the DC outputs, if not grounded.) This could easily kill a component. Sure, if a manufacturer provides a proper grounded SMPS, you'll be fine most of the time, but what about when someone has a bad ground in their receptacle and doesn't know it? A transformer-based unit is less likely to cause problems in that situation.

Finally, I do believe that transformer-based supplies are more reliable. I'm not saying that SMPSs are inherently unreliable, just that a transformer is more reliable, all else held equal. (Obviously, all bets are off either way if something is made badly.)


We just got some Weller WSM 1 stations at work, and they use a simple ungrounded external power brick, seemingly relying on a separate potential equalization jack for true grounding. Not sure how I feel about that...

[DW1961]

Not particularly, it's 120V +6/-13% in USA.

Ok so it's 107V to 127v . That's not going to cause any damage to a 120V device. I use to live in Northern California near the coast, 80 miles south of the Oregon border. Yeah, up there it fluctuates and you have power outages too, usually in the winter storms. I always had a UPS, always. And, it did get used too. In 2006 we had a class 1 hurricane, for example. But, in the winter you could expect your power to go out at least once or twice a year, and I saw many times voltage at 110, but that's still in spec. I never saw it go to 107, but it could for a short time. Again, not worried about voltage.

Anyway, I live in a big CA city now and the power has never gone out in over 5 years. The city has a very stable power grid and mostly underground wires wince 1974.

[DW1961]

To me digital  when it comes to soldering stations is using a microcontroller or some logic chip to control the temperature of the tip ...

an analogue soldering station (like Hakko 936 for example) uses a triac, an opamp and a regular potentiometer to adjust the temperature of the tip
 
a digital soldering station would use a microcontroller to read the temperature from soldering iron tip and 2-5 buttons where some buttons may be temperature "presets"... some stations are branded digital just for having a temperature readout on a lcd display.

I have two soldering stations, a genuine hakko 936 and a pace hw50, both with transformers... i like the weight, makes them harder to move around on the desk.

Good catch and the one I'm talking about probably does use digital temperature control but also a large transformer to generate heat. I was mainly wondering about the heavy transformer types vs non transformer types, regardless of how they control heat.

[mariush]

Good catch and the one I'm talking about probably does use digital temperature control but also a large transformer to generate heat. I was mainly wondering about the heavy transformer types vs non transformer types, regardless of how they control heat.

It doesn't have to be that heavy, they could easily use a toroidal transformer or a R type transformer to reduce weight .. the toroidal transformers don't use steel sheets so they'll be much lighter.
They are however more expensive to make, and more expensive to attach to a case while taking care of vibrations and all that.. basically you need extra hardware to mount a toroidal transformer and that adds cost.

Regular transformers are just cheaper, easier to wind using automated machines, easier to screw to the base of a soldering station and all that.