Battery powered wireless microphone

[bdevero]

Hello everyone,

I have been thinking of a project for the past month and I decided today to reach out and ask for help to get it started.

I have an audio device that is designed to run on 12 to 18 v DC input 140 mA supplied by an AC adapter wall plug.

I would like to convert this device to run off an 18v rechargeable battery designed for use with a cordless drill.

I am not very knowledgeable about electronics, though I believe this project can work. I want to make sure I am doing it correctly and safely.

Can anyone give me any advice moving forward on how to tackle and complete this project?

If I can get this wireless audio receiver to run on battery power, I will use it to send wireless audio from a mic to my iPhone during live video streaming. The base unit (wireless receiver) will be mounted on the tripod along with the battery power.

Thanks for any responses,
Brad

 

[GreenGiant]

It should be as simple as just making a plug that can connect to the battery and use the existing wall wart receptacle on the mic

Before doing this though... where are you getting the 140 mA from, is it on the mic or on the wall wart?

 

[bdevero]

More details

Thanks for the response.

The wall wart for the wireless mic receiver unit says output 12v DC 500mA.

The audio receiver says on it: DC in 12-18v 140mA. The wireless microphone, which is separate from the base unit, runs on a standard 9v battery.

I would like to use the 18v cordless drill to power the base unit so that the entire setup can be mobile.

So it would be as simple as building an adapter for the battery to plug in to a cord that connects to the receiver? Do the numbers look correct to operate safely?

Thanks again,
Brad

 

[GreenGiant]

It sounds like you should be able to just make an adapter to go from the battery to the receiver, I cant promise that it will work (without testing it personally I cant promise), but from the information that you have provided it sounds like that should work.

 

[CDRIVE]

If 18V is the absolute max limit for this device you may want to consider running it off a 14.4V battery. If you use an 18V model you will probably exceed 18V when fully charged.

Chris

 

[GreenGiant]

I wouldnt think it would be over 18V, I know that all lithium battery packs will max out at 18V total and as soon as you remove it from the charger it will drop to around 17.6 and hold there fairly seadily, but good recommendation CDRIVE

 

[CocaCola]

If 18V is the absolute max limit for this device you may want to consider running it off a 14.4V battery. If you use an 18V model you will probably exceed 18V when fully charged.

Or just put a few series diodes, at a few 140mA they won't even get all that warm and it buys you a margin of error for a nickle...

 

[CDRIVE]

I really wasn't sure what an 18V lithium would charge up to. I assumed it was > 18V. That said CC's safety solution is cheap insurance.

Chris

 

[userqq]

seems to me like the 18v cordless drill battery would have too much current.

 

[CDRIVE]

seems to me like the 18v cordless drill battery would have too much current.

A load uses only as much current as it needs. If a device operates on 18V @ 1A it doesn't matter if the battery can deliver 1000A.

Chris

 

[(*steve*)]

seems to me like the 18v cordless drill battery would have too much current.

You're new here userqq. Some new members want to jump in and be helpful, that's great.

However it pays to ensure that you're not overextending yourself when doing so.

Please try to offer advice only when you understand the issues well enough to teach people (i.e. very well)

 

[bdevero]

Update to wireless mic

Update:

I decided to hook up the battery to the wireless receiver and it worked. I can deliver wireless audio to my iPhone using the battery battery pack. I haven't tested the battery life, but I suspect it will last a while. I plan to test it out soon.

My only complaint is a slight hum or buzzing heard in the recording. It is not too loud and it is also present when the unit is plugged into the wall. It could be just a fact of life for the gear I have, but if not:

Does anyone have an idea of how to adjust the circuit to eliminate the hum, or what I should check for to see if this is a factor?

Any other ideas are also welcome. I will post a picture once I get the device a little further along.

 

[CDRIVE]

My only complaint is a slight hum or buzzing heard in the recording. It is not too loud and it is also present when the unit is plugged into the wall. It could be just a fact of life for the gear I have, but if not:

Are we to understand that this hum / buzz existed prior to powering from the battery? Describe the buzz / hum.

Chris