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New Product Prototype

Paul Barber

Jan 4, 2017
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Hello everyone,

I am a complete newby to electronics (I am a plumber!!) so I am hoping someone maybe able to solve a few problems I am having. I am making a prototype for a new product that consists of a simple 3v dc buzzer, rechargeable 3.7v dc Lipo battery and a small dc relay on/off pcb controlled by a remote control handset with on/off button. (A bit like what you get with automatic gates or garage door.

The problem I am having is that due to the design of the product, once the electronics and battery are fitted inside the device, there is no way of ever being able to get to any of the components or isolate the battery with a simple manual on/off switch (like a remote controlled car has). This means that the battery life is very poor and the device is running dead, even when not in use, after 2 days. Is there anyway of prolonging the life of the battery by adding electronic components or have I got to fit an on/off switch?

Is it possible to have a switch that is operated by say a magnet? or remotely operated somehow? or could it be switched on and off from the charging point which is accessible?

Thanks for reading and all help much appreciated.

Paul
 

daberbaber

Feb 2, 2012
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Most controls are intermittent use only...they do not need to be on continuously. That makes battery life extended by nature of the design. If the press to active button is essentially a power on off contact, then you are only powering up the handset to activate the relay control board that I assume is connected to the buzzer. Or is this relay board the one you want to have powered off or down until activated? If this is the case, then you have to place a very low current drain receiver(for the signal from the handset) in the power on circuit of the relay board so it is only turned on when a signal arrives from the handset. Most of these receivers should be CMOS and have enough capability to turn on an electronic switch device that powers on the relay board.
 

AnalogKid

Jun 10, 2015
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Without more details about the circuit and components, it really is impossible to say. If it is just a battery, button, and buzzer, there should be zero current when the button is not pressed. What else is on the relay pcb besides the relay?

Schematic?

ak
 

Paul Barber

Jan 4, 2017
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Hi both and thanks a lot for your replys. I think I need to give you more detail. Basically I bought a mini remote control switch on eBay, attached is a pic. On the red and black wires from the remote switch I have connected a 3.7v Lipo battery and from the yellow and blue I have connected had buzzer. When the big red button on the handset is pressed the buzzer sounds.

When the device is left idle and not used something is draining the battery.

Hope that makes sense and thanks again
 

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AnalogKid

Jun 10, 2015
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It is a radio receiver. Since it doesn't know when you might press the button, the receiver is on and active all of the time. The output switch probably is a small power MOSFET, and consumes almost nothing between activations.

ak
 

davenn

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Sep 5, 2009
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Hi both and thanks a lot for your replys. I think I need to give you more detail.

can you please give the link to where that item is so that people here can better review its capabilities
 

Paul Barber

Jan 4, 2017
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https://www.ebay.co.uk/itm/231784559855

Here is the link for the item I have bought.

Thanks ak, yes I agree it is draining power because it is always listening for a signal to be activated. Is there anyway to save battery power or is manual switch between the battery and the receiver the only option?
 

davenn

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Is there anyway to save battery power or is manual switch between the battery and the receiver the only option?

well if you switch the receiver off, then it wont activate when the fob transmits
 

Paul Barber

Jan 4, 2017
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Yeah but I mean a switch to turn off the receiver when the device is not in use and then turn the switch on when I want to use the device. Like a rc car or something.

The problem is though the switch will not be accessible to manually turn on or off because it will be sealed inside a unit.
 

Paul Barber

Jan 4, 2017
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If this is the case, then you have to place a very low current drain receiver(for the signal from the handset) in the power on circuit of the relay board so it is only turned on when a signal arrives from the handset. Most of these receivers should be CMOS and have enough capability to turn on an electronic switch device that powers on the relay board.


I am interested in this idea. Is there something I can add to my circuit "a low current drain receiver"? Or should the receiver I am using now be "a low current drain receiver"?

Thanks again everyone
 
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Alec_t

Jul 7, 2015
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What type of charging socket are you using? It may be possible to rig something so that a dummy charging plug would switch the receiver off. A switched 3.5mm jack could do this, as used on some mains/battery portable radios.
 
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BobK

Jan 5, 2010
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I am missing something here. If you can wire out a charging jack, why not a switch?

Bob
 

BobK

Jan 5, 2010
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Also, the receiver uses 5 to 7mA. A 2500 mAH battery would last 2 weeks.

Bob
 

Paul Barber

Jan 4, 2017
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What type of charging socket are you using? It may be possible to rig something so that a dummy charging plug would switch the receiver off. A switched 3.5mm jack could do this, as used on some mains/battery portable radios.

It's a 1.25 micro jst two charger from a very small drone. I am not sure it would be possible to fit a 3.5mm jack connection due to the shape and design of the device but I will look into that thanks. So is there an on/off switch built into the jack charging port?

Thanks again
 

Paul Barber

Jan 4, 2017
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I am missing something here. If you can wire out a charging jack, why not a switch?

Bob


It's hard to explain but due to the shape and design of the product even the charging port has caused me major headaches. Another wire for a switch is possible but I would need a very very small switch as to not change the external shape of the product which I have been unable to source. I need an on/off locking switch that is about 5mm long max. Any suggestions on suppliers on line.

The batteries are 3.7v 150mah due to the physical size of the battery. I need super small bits for this project do that might explain the dead battery after two days.

Thanks for your help Bob
 

Paul Barber

Jan 4, 2017
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An option could be a switch that can be pressed through the outer skin of the device as this is a flexible material.

I believe it is called a tact switch? I need a small tact switch that you would press and hold for 5 seconds to turn on the device and then press and hold for 5 seconds to turn off the device.

Where is the best place online to buy something like that and what is i
 

Paul Barber

Jan 4, 2017
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Hi guys

Just wondered what your thoughts were on not having an on off switch atall but just having a lipo battery 3.7v and say 1000mah . Would this last longer than the 3.7v 150mah battery I currently have that last about 2 days.

If this is a better option for me is it bad practise to let a lipo battery run completely flat before charged? If the device was left for say two weeks and went completely flat would that matter?

Thanks again everyone
 

BobK

Jan 5, 2010
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A lipo battery will be damaged by discharging too far. But many have a built in protection circuit that prevents this, as well as overcharging. You should only consider those with protection.

Bob
 
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