I placed this project before and did not follow advice and sent payment for this project outside Freelancer directly to the winning [url removed, login to view] has since refunded me 100.00 but The job was not done so I will place this project again.
I do have a diagram of a simple circuit using a transistor.(BC558) The diagram does not provide any diodes to protect the transistor so you may have a better way.
Needs of the alarm:FIRST OF ALL I DO NOT WANT JUST A DIAGRAM, I WANT A PHYSICAL ALARM.
(1) Description of operation:
The alarm needs to be a normally closed circuit, which would alarm if the wire were cut. A wire loop made of insulated wire, would be intertwined with the vents in the covers.
Should this be cut, the alarm would sound until the battery went dead. I don’t believe the wire gage it would use is important because of it being battery powered.
(2) Component needs:
(a) It is important for the alarm to use a readily available and cheap IC like a 555 IC or a transistor like a BC558.
(b) It must have a loud alarm, 132 decibel like found in personal alarms.
(c) The alarm would need to be battery powered by a physically small battery, maybe a 9 volt battery.
(d) The box containing the alarm must be as small as possible and the case needs to be easily obtainable and cheap. All must fit in a plastic containment of 5 inches by 5 inches or LESS.
The alarm would be mounted in an area where there are already electronics components which are protected from the weather, so the container of the circuit is not subjected to the elements, but is subjected to vibration and heat up to 110-120 F.
(e) The place where the wire loop attaches needs to have two terminals with metal screws or “screw-downs for “loop wire” (could be like the ones used for stereo speakers) (when wire is cut alarm will sound) I will be using possibly a gauge of wire like insulated telephone wire (#24 gauge) or slightly larger
(f) This must have a “test” button button (push=on; release=off) and a way to cancel alarm by the owner. (micro-switch push=on , push=off) or tiny toggle switch
(g) short alarm for low battery
(h) very low battery drain while circuit is in alarm-off mode
(i) The components must be cheap and easily obtainable costing no more than $5.00 total
Our budget for this project is 300.00.I will need three duplicate alarms sent to me by priority mail.
Also, I must have complete instructions concerning construction so I may build it myself.
If you would like to know me by reputation look at my Ebay ID My Ebay ID is blupkwy.I was one of the original sellers on Ebay and was a Power Seller for many years.I thank you in advance for your help.
Using a 555 ic is not written in stone, you could suggest a better,cheaper method.I do want the loud alarm(at least 130 decibel) and all components in the same container.
Do not worry about getting paid, I honor my commitments,you will get paid promptly.
I can design this circuit and build required prototypes. I have an excellent knowledge in this area after working for a large UK company making this type of product.
21 freelancers are bidding on average $340 for this job
Iam electronic circuit designer,I had finished car alarm product that used mobile phone to contact with ownner,your project is simple ,i will happy if i can help you,i has addition alarm idea for you,thanks,blupkwy