Shock Safety Belt

Introduction: Shock Safety Belt

About: I create only useful products.

Electronics make our life very easy but i never thought it can save our life too.

In this my project i show how to save our life from electric shock.

This project is very simple,Its turn off main switch or cut off power if you bi-mystically touches high voltage power line.

Step 1: Principle

Human receive a electric shock when he or she is part of part of electric circuit.Human body resistance changes with person to person and several more environmental condition.But normally dry skin resistance is near about 100K ohm.

if you came contact with 230V AC voltage(RMS 160V) ,as per ohm low the current flow from your body is


I=160/100K (R=100K human body resistance)


This small current sense by transistor and switch the mains power supply off by using RF link.

Step 2: Schematic Dig. of Transmitter Section

We saw the purpose and principle of project,Now lets understand its exact working.

9V battery used as power supply for the project which is connected via IC7805 to regulate constant 5V supply.

The BC107B act as a switch.The BASE terminal is connected to human body.At COLLECTOR(C) terminal +5V supply is provided and EMITTER(E) terminal is connected to the DATA pin of 433MHz transmitter.433MHz transmitter powered by 5V vcc.

Even small(1mA) current through BASE terminal is enough to conduct collector to emitter current.Which produce DATA signal at the DATA pin of 433MHz transmitter.

Step 3: Schematic of Receiver Section

433MHz receiver power up by +5V supply.The DATA pin of receiver is connected to the BASE terminal of transistor C2073. If DATA is present then it cause to produce current from C to E otherwise remains ideal.At emitter terminal 9V relay is connected which operates when +9V are applied across it and then it switch from NC(normally connected) to NO(normally open). At initial condition relay is always in NC condition,means the mains power supply is connected when it shifted to NO it cut the power supply.





9V relay

433MHz transmitter

433MHz receiver

Connecting wires


Step 5: Lets Make It

Start with receiver section.

place component one by one.

Step 6:

place all components and solder it as per schematic dig.

Step 7: How to Make Safety Belt(transmitter Section)

find belt and buckle from old bag pack.

Step 8:

Lock the belt in buckles in such manner that it can be wear on wrist.

Step 9:

ok its ready.

Step 10:

Insert the Base terminal of BC107B from top of the belt.

Step 11:

and bend it with parallel to belt surface.

so it can easily comes in touch with human body.

Step 12:

Insert 433Mhz transmitter in socket.

Step 13:

Arrange all circuitry as per schematic and place on a belt

Step 14:

i use wire and glue for fixing it.

you can use anything

Step 15: How to Make Antenna

use 50ohm wire to make coil of 6.5mm about 20mm length.

sorry,i forgot to clicks photo at the time of making antenna.

but you can make it with help of google.

Step 16: How to Test It

connect 100K(2W) resistance terminal to the base of BC107B and another terminal insert in 230V AC mains plug.

take precaution while testing, use insulating gloves.

At receiver side use bulb to connect in series with 9V relay and observer it.

when you connect resistance to mains power supply the bulb turn off.


Step 17:

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    6 Discussions


    Reply 5 years ago on Introduction

    Thanks for showing interest.

    But friend seamster ,it has some error.

    please wait for my next instructables,i will update it in next instructables.

    Thank you.


    5 years ago on Introduction

    Be aware that 433MHz is a deregulated band for low power devices of all sorts (wireless alarms, keyfobs, temperature sensors, remote controls for garages etc. etc). as well as higher powered amateur radio transmissions, and so you may find your devices powering off for no apparent reason, as this device doesn't use any encoding, just presence of signal.

    Also: As the signal into the BC107 is 50/60Hz AC, turning the transistor on and off, won't it transmit that signal to the far end relay, and cause it to buzz at 50/60Hz? This would be bad for connected equipment. How do you stop this?


    Reply 5 years ago on Introduction

    Yeah,MikB i got my mistake when i test it with 230V AC mains supply.Up-to the next week i will publish it with error free design.

    Thank you


    5 years ago

    Just looking at the mathematics of this, 230v , the nominal mains in the UK is then likened to 160v. I am not sure when this comes from. 230v rms ac means that the effective voltage if it were dc. The mains is a sineusoid centred on 0. The mains actually peaks at 320v back to 0 then to -320v returning to 0. The effective dc is 230v. should not the calculations be using the peak or rms not 160v?