My kid's bubble blowing machine runs on 8 AA batteries which it chews through in less than an hour. Also, only the first 15 minutes seem to make a satisfying amount of bubbles and after that, it fades to only a few bubbles every now and then.

I have carefully wired it to a 12V DC adapter and have housed all connections so they're water-tight.

When I initially tested this setup by holding the AC wires to the motor, all seemed to work well and fine. However, now that it's all soldered up, it pulses with intermittent bursts of power.

How do I fix this? Do I require a voltage regulator? If so, can it be applied anywhere down the power line?

Please know I am completely novice when it comes to the nuances of electrical engineering, so if possible, keep it layman. Thanks!

Thank you all for your replies. I am still trying to learn the ropes here at SE but I'd like to upvote all of your replies. Apparently I cannot yet.

From what I collect from my answers, I need a DC power supply that exceeds 1 Amp. I thought that anything that plugged into a wall was AC.

Here is a photo of the info from the adapter I have connected:

12V Adapter

It says that it's 1.5A. Is this not sufficient? It does not indicate 12VDC. Is this my problem?

If I need a 12VDC adapter that outputs 2A and I was to purchase one, can I simply splice it in at an earlier stage than having to take the whole toy apart again and rewire throughout? Will the wires from this adapter, in other words, handle the throughput of the new adapter?

Thanks so much again everyone.

  • \$\begingroup\$ The one you posted is 120V (Mains Voltage) AC (the ~ symbol) In, 12V DC (the 3 hyphens with a line over it) Out yes. If it's stopping and starting then it's a sign that there is 1) a short or 2) the load is too big for the supply. I use a 1 Amp supply just like that for a rotary tool, and if it stalls out, the supply cuts off, and will turn on a second or two later. That's a short circuit protection circuit working. \$\endgroup\$ – Passerby Apr 2 '16 at 21:21
  • \$\begingroup\$ When you say you held the wires to the motor, do you mean directly to the motor of the toy, or to the contacts where the batteries normally connect? If its the latter, then you probably need to resolder everything from scratch, you may have bridged/shorted or otherwise made a mistake when you wired it up. \$\endgroup\$ – Passerby Apr 2 '16 at 21:23
  • \$\begingroup\$ The latter. When I held the raw wires, I did so directly to the motor. Do you feel that the adapter I used is sufficient and I simply need to re-solder? \$\endgroup\$ – Brenn Apr 2 '16 at 21:38
  • \$\begingroup\$ The latter means you connected to the battery holder. The former meant the motor, skipping any circuit board. In the latter case resoldering may have helped. The the former, something else may be wrong. \$\endgroup\$ – Passerby Apr 2 '16 at 22:25
  • \$\begingroup\$ Next step is to get a loan of a multimeter and actually measure the current being drawn. \$\endgroup\$ – Transistor Apr 2 '16 at 22:26

Assuming that your AA batteries are alkaline cells, the bubble machine is pulling about 1 amp. AA cells are (roughly, it depends on current levels) about 1 amp-hr capacity at 1 amp, so 1 amps times 1 hour is about right.

Take a close look at your AC adapter. It will probably say 12VDC and some number of amps. In this case, it's probably in the 1 to 2 amp range, and closer to 1 amp. If this is so, the adapter is unable to produce 12 volts at the current required. This results in weak motor drive and sounds about right for your problem.

The only solution, if I'm right about the adapter, is a different adapter with a higher current rating and the same voltage rating.


My kid's bubble blowing machine runs on 8 AA batteries which it chews through in less than an hour.

A quick web search for AA alkaline 1-hour discharge gives an article by Powerstream which suggests that the batteries will go flat in less than an hour at 1 A discharge. I suspect your bubble machine is pulling 1 A.

I have carefully wired it to a 12V AC adapter ...

I hope you mean a mains-powered DC power-supply.

... it pulses with intermittent bursts of power. How do I fix this?

Check that the power-supply is rated at > 1 A at 12 V DC. If not replace it.

Do I require a voltage regulator?

No. Voltage regulators are used where a very stable voltage is required. Your bubble motor won't care if it's plus or minus a couple of volts.


...runs on 8 AA batteries...

I have carefully wired it to a 12V AC adapter and have housed all connections so they're water-tight.

Batteries are direct current (DC). A 12V AC adapter is entirely inappropriate for this, use a 12V DC adapter.

Or, if this an issue of semantics and your adapter does in fact output 12V DC (and it's an AC adapter because it converts AC to DC, the terminology is unfortunate), see WhatRoughBeast's or transistor's answer.

  • \$\begingroup\$ He is. He just misspoke. \$\endgroup\$ – Harper - Reinstate Monica Apr 2 '16 at 22:29
  • \$\begingroup\$ Alright, just wanted to make sure. In fact, I wouldn't even say OP misspoke, what he said was accurate, it's just an unfortunate consequence of terminology. \$\endgroup\$ – uint128_t Apr 2 '16 at 22:31

5-amp ammeters are common and cheap. I recommend owning one. It would quickly settle the question of how much power the motor draws. From there you can figure out the right DC power supply.

The market for LED strips and other lighting is a very good source for 12VDC power supplies of more amperage than you find in old wall-warts.

Though, of course, 12VDC power supplies can be paralleled... if you have several old wall-warts lying around.


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