I'm thinking about building a gate open beeper to help insure that the gate is not left open, letting our dog out. Especially when I take the green waste bin out/in or carry materials in/out of the yard and I forget to close the gate.

What I need is a low frequency beeper between 400 Hz and 1000 Hz. Because of my high frequency hearing loss, I can hardly hear piezo buzzers that buzz at 2500+Hz.

What I hope to build is a battery operated beeper at about 700Hz using a magnetic reed switch for gate open sensor and for outdoor use. I think the battery could last a long time since power to the beeper would only be applied while the gate is open. Not sure if a 9 volt battery would be sufficient.

I have not been able to find a low frequency beeper. I did buy a 400 Hz buzzer from Amazon but when I received it, I discovered that the volume of the buzzer was really weak with the buzzer on the work table. The volume depends on the unit being mounted "firmly" to a surface that can be vibrated to amplify the sound of the beeper. Not a solution for my problem.

Any ideas?

 

The gate-open sensor will not be so much the challenge as the sound generation portion, given the lower frequency requirement. My guess is that size, power consumption, and weather resistance will be the big issues.
One option could be a variation of an electronic siren such as are often used on vehicle security systems. A simple oscillator driving a transistor pair can deliver a few watts to a small horn speaker. The problem immediately is the power supply, which will be quite a bit more than a single 9 volt battery.

An alternative could be adding a spring arrangement to close the gate after you pass thru. Non-electronic, but completely automatic.

 

Any ideas?

Hi S8,
Why not fit a gate closure spring?
E

https://www.amazon.co.uk/s?k=gate+c...x=gate+closing+spring,aps,92&ref=nb_sb_noss_1

 

The gate-open sensor will not be so much the challenge as the sound generation portion, given the lower frequency requirement. My guess is that size, power consumption, and weather resistance will be the big issues.
One option could be a variation of an electronic siren such as are often used on vehicle security systems. A simple oscillator driving a transistor pair can deliver a few watts to a small horn speaker. The problem immediately is the power supply, which will be quite a bit more than a single 9 volt battery.

You listed all of my concerns for a battery operated, low frequency audible alarm. Hoping that the ingenious gurus on this forum can think of a battery operated, low frequency alarm that will work.

An alternative could be adding a spring arrangement to close the gate after you pass thru. Non-electronic, but completely automatic.

That was my first idea. But a spring closed gate has several disadvantages:

1. Would need a hook to hold the gate open while I take the green waste bin in/out of the yard to the street.
2. Similarly, hold the gate open while I carry garden materials in/out of the yard.
3. Then I would forget to unhook the gate, the same as forgetting to close a non spring gate.
4. Spring loaded gate slams shut, stressing the stopper on the post.

So I figure that an audible alarm will remind me to always close the gate after I take stuff in/out of the yard. Plus no slamming of the gate.

Thanks.

 

Hi S8,
Why not fit a gate closure spring?

Please see my response to MisterBill2. Thanks.

 

Please see my response to MisterBill2. Thanks.

My "cheating trick" when dealing with spring-closed doors, when carrying a heavy load, or rolling a cart, has been to back thru them so that I do not need to use my hands to hold them open. That tends to work fairly well. Of course, some gates mat need a "De-burring" treatment for that scheme to be comfortable. Heavily galvanized fencing and rough cut lumber are two materials that often need attention.

 

Maybe use a car horn - they tend to be fairly waterproof. If it's too loud you can dampen with foam. When the gate opens, build in a delay before it turns on, and maybe an astable to beep on and off.. The delay could be done with a 555 monostable and the beeping with a 555 astable - there are 2 x 555 ICs in a 556 IC. Not enough current output for the horn, so use a relay or transistor. 12V car battery, maybe trickle charged with a solar panel available for that purpose.

 

There are low frequency (520 Hz) smoke alarms for people with high frequency hearing loss. Perhaps buy one of those and repurpose the alarm device. It would be plenty loud.

 

Hi. On the subject of slamming gates you could use something like this.
https://www.lowes.com/pd/WRIGHT-PRO...tic-Screen-Door-and-Storm-Door-Closer/3081419
As for an electronic circuit, I built the same sort of thing for my freezer along with an adjustable hammer, the part that touches and activates (or deactivates) the freezer door alarm. It times out around 80 seconds, which means my wife can open the freezer and put something in or take something out without setting off the alarm. Exceed the time limit and it starts squawking. Close the door for a minute and it's reset and ready to do its job again. I used a microswitch because they're easier to find in double throw configurations whereas reed switches are a little harder to find but not impossible; but they lack the adjustability of having something touch a switch. I have to find the schematic for that circuit, but when I do find it I'll post it. The best thing about the freezer alarm is that the battery is completely disconnected when the door is closed. So a 9V battery seems to last quite a long time before it needs replacement.

[edit]
The screen door closer has an adjustment screw that determines how fast or slow the door closes. You can have it set to close very slow allowing you time to open the gate and get the barrel through before it closes too much. It also features a "SLAM SHUT" that when it gets nearly fully closed the door will slam. You determine that point by adjusting the position of the attachment to the gate. You can have it so it never slams or you can have it slam when the door has just a few inches left to close, or any reasonable amount of slam. Too late a slam and the door may never accelerate enough to make the locking mechanism to lock. My cats love when I set mine wrong, they can always push the screen door open. But I've made the necessary adjustments and make sure it closes fully. A bit of a slam but not bad.
[end edit]

 

Put a sign on your door that reads "close the gate".

 

Still looking for more information on what I used.
SW1 is a microswitch set up using the C and NC contacts. When the door is closed the switch is depressed and no contact is made. The alarm stays silent and no power is used. When you open the door SW1 changes and closes the contacts (C/NC) and the timer starts. I don't know why I didn't capture the values of the components other than the 2N7000 N-Channel MOSFET and the 9V battery. The SonAlert was purchased on Amazon and it has a fairly high frequency, one I can still hear, but not well, due to tinnitus, same as you probably have. But this may be a starting point for you.

The chip is an LM385. R1/R2 set up the reference voltage. C1 charges through R3 at a pre-determined rate. When the voltage on pin 3 exceeds the reference voltage on pin 2 pin 1 output activates the MOSFET. The MOSFET in turn provides pathway to negative and thus turns on the alert.

I'm going to get a lot of grief because this is not a schematic. (SEE POST #12) The purpose of this drawing was to lay out the components using a pre-made perf board. The only things not mounted to the board are the battery and the alarm.

 

OK, here's my schematic (Less resistor values and cap values) OH! The battery is 9V.

 

A car horn or a motorcycle horn will draw several amps, and be wayy to loud. A bicycle horn would be much more appropriate, and also probably include the battery compartment that may even be weather resistant. AND the whole assembly may cost less than the parts to build anything in a weatherproof enclosure. In addition, using a bike horn package will reduce the external requirements to simply providing the correct switch. I suggest looking at a security systems distributor for the gate switch.

Of course, the dog will soon learn that when they hear the horn sound, the gate is open.

 

It would seem that a continuous sounding horn would be annoying, both to you and any neighbors.
You could add a timer circuit to activate the horn for a short beep every few seconds.

 

I have some of these. Automotive squeaker. They might pull too much power but it is place to look. There is also the seat belt not connected squeaker. Place these at head high and you will hear them.

 

Of course, the dog will soon learn that when they hear the horn sound, the gate is open.

LOL; yes! My neighbor had an annoying barking dog. He put a shock collar on him. He quickly learned to be quiet when wearing the collar. But it was recommended not to put the collar on the dog for more than 12 hours at a time. So the dog learned that when not wearing the collar it was permission to bark. And this dog would aimlessly bark at nothing. Just felt the need to express himself. THEN other dogs in the neighborhood would hear him howling and they'd start. Which would egg him on.

Perhaps a more expensive route to go would be to use a bluetooth or Wi-Fi transmitter that would signal you on your phone when the gate was open. No need for audible alarms or anything else that the dog would learn from.

 

The chip is an LM385

LM385 ?
Do you mean a LM358 ?

 

Maybe use a car horn - they tend to be fairly waterproof. If it's too loud you can dampen with foam. When the gate opens, build in a delay before it turns on, and maybe an astable to beep on and off.. The delay could be done with a 555 monostable and the beeping with a 555 astable - there are 2 x 555 ICs in a 556 IC. Not enough current output for the horn, so use a relay or transistor. 12V car battery, maybe trickle charged with a solar panel available for that purpose.

I installed a motorcycle horn in our van for audible auto door lock confirmation. That horn's spec was 1.5 amps. Too much current draw for this gate battery project. Thanks.

 

I installed a motorcycle horn in our van for audible auto door lock confirmation. That horn's spec was 1.5 amps. Too much current draw for this gate battery project. Thanks.

Are you looking for a ready made product?

 

There are low frequency (520 Hz) smoke alarms for people with high frequency hearing loss. Perhaps buy one of those and repurpose the alarm device. It would be plenty loud.

That is a genius idea! Never would have thought of using a smoke alarm with low frequency beeper in a million years. And some smoke detectors use a 9 volt battery. Perfect! I'll look into this solution closely. Thanks!