Is it OK to use an A/C adaptor to power the AxonII?

[Kelpy]

When I'm playing around with the programming on my AxonII, my batteries are forever going flat, so I was wondering if it is safe to use a 6V regulated A/C adaptor to power it during those times?

[Soeren]

Hi,

When I'm playing around with the programming on my AxonII, my batteries are forever going flat, so I was wondering if it is safe to use a 6V regulated A/C adaptor to power it during those times?

That depends.
If it's giving a reasonable regulated DC out - measure the output voltage, both idle and with a load of eg. a 6V lamp of a suitable rating.
The adapter probably have a rating in W or VA written on it, what does it say and what else is written on it?

The more info you provide, the better we can help,

[Kelpy]

Thanks for the reply, Soeren.

It is a multi switching adaptor with selectable output of 6, 7.5, 9, 12, 13.5 and 15 volts
Output current 5000mA and 60VA MAX.
It was quite expensive (I think) and has different size jacks which, depending on which way around you insert them, can be positive or negative centre.
The model number is P007MB.
Hope this helps.

Cheers.

[macdad-]

You said it was a switching wall-wart, so it should be quite accurate. The max Amp rating will vary based upon the voltage output, but that shouldn't be to much of a concern. Just be sure to check the polarity of the jack. 

[z.s.tar.gz]

You said it was a switching wall-wart, so it should be quite accurate.

I wouldn't go that far. The fact that it's switching shows how the voltage is converted but not whether it's regulated.
When it comes down to it the only way to tell is to either thoroughly test it or open it up and do some research.

[macdad-]

You said it was a switching wall-wart, so it should be quite accurate.

I wouldn't go that far. The fact that it's switching shows how the voltage is converted but not whether it's regulated.
When it comes down to it the only way to tell is to either thoroughly test it or open it up and do some research.

Right, but switching wall-warts are(from experience) relatively regulated, but still what about the onboard regulator on the Axon II?

[Soeren]

Hi,

The model number is P007MB.

I see it as a 75VA unit, but your 60VA unit may be an older model, or it's from the 5A max. at 12V.
Just go ahead and use it, it will be fine, there's a regulator on the Axon2 anyway AFAIK.

Just for the sake of safe conduct (towards your controller board), it wouldn't hurt to actually measure the output anyway - I have a sneaky suspicion that it's a Chinese made PSU and well... Better safe than sorry.


And for the regulated/not-regulated debate on switchers... All switch mode supplies are regulated - period.

[Kelpy]

Many thanks all.

I will do as you suggest, Soeren, and put a multimeter on it first.

Cheers.

[Admin]

Just for the sake of safe conduct (towards your controller board), it wouldn't hurt to actually measure the output anyway - I have a sneaky suspicion that it's a Chinese made PSU and well... Better safe than sorry.

Agreed. I bought one off the streets in Thailand and the output was many volts higher than the actual setting - enough that it fried a circuit of mine. Lesson learned

[cyberfish]

That may not be the adapter's fault.

Unregulated adaptors (most of them are) are designed to produce something close to the rated output voltage under full load.

Under minimum load, it's usually quite a few volts higher.

[Soeren]

Hi,

That may not be the adapter's fault.

Unregulated adaptors (most of them are) are designed to produce something close to the rated output voltage under full load.

Under minimum load, it's usually quite a few volts higher.

Don't mix apples and oranges.
I'll repeat... All switchers are regulated.

An unregulated supply do have a certain regulation (funny, it's called regulation, as it's actually the exact opposite) due to electrical and magnetic impedance.

A switcher IS a regulator, whether it takes its input from the afforementioned hunk of iron, or off-line through rectifying, chopping and running the power as a high frequency through a ferrite core transformer (or powdered iron core if running at a lower "high" frequency).
An unregulated switch mode converter would saturate at max. voltage possible and whenever the load was less than the throughput, the voltage would betoo high (reaching the limit possible with the design at hand). Loaded too hard, even 0.1% too hard (relative to throughput) would make the voltage slide down until it was in balance with the impedance of the load and with a varying load, like most are, the voltage would follow the load current.

Try for yourself... Make an oscillator with eg. a 555, make it 50% (or some other nice number) duty cycle for easier calculation of test results. Let the output of that drive a MOSFET used as the switch element in a simple switcher (L, C and a fast diode).
Vary the load on the output and measure the voltage while doing it.
A very easy experiment and one that should open your eyes to why you cannot buy an unregulated switcher.

[cyberfish]

Yeap I know how switchers work.

My post was in response to

Agreed. I bought one off the streets in Thailand and the output was many volts higher than the actual setting - enough that it fried a circuit of mine. Lesson learned

He didn't say it's a switcher, and by the sound of it, it probably isn't (I doubt anyone can make a switcher that bad - most of the circuitry is just in the controller IC).

[Admin]

Yeap I know how switchers work.

My post was in response to

Agreed. I bought one off the streets in Thailand and the output was many volts higher than the actual setting - enough that it fried a circuit of mine. Lesson learned

He didn't say it's a switcher, and by the sound of it, it probably isn't (I doubt anyone can make a switcher that bad - most of the circuitry is just in the controller IC).

I didn't open it up, but I seriously doubt it had anything more than a transformer + rectifier. I also didn't test it while under any load . . .

[cyberfish]

+ filter of course .

But yeah, it's probably unregulated. At no load the voltage is designed to be much higher. If you look at it under an oscilloscope, the ripple should be quite bad under load as well.

To use this kind of adapters, you'll probably want to regulate it yourself. Unless your circuit really doesn't care about the voltage fluctuations and noise (eg, a lightbulb, or LED, or heater).