Ambulance Lights

This article is about ambulance lights. It does not include making the sound generator for the ambulance siren. Just the lights.

If you want to know how to make an ambulance siren sound generator then you can click on this link from Weird Circuits: https://weirdcircuits.blogspot.com

I borrowed the circuit from the Weird Circuits group and recorded the ambulance lights video with the siren:

Step 1: Make the Stand

I purchased a gear motor from Jaycar Electronics (https://www.jaycar.com.au) for $10.

I made the stand from 1.5 mm insulated metal wire:

Step 2: Make the Circuit

I connected 5 LEDs in series with two 10 ohm resistors (20 ohm total).

The total current is:

Itotal = (Vs - Vled) / Rled = (3 V - 2 V) / 20 ohms = 1 V / 20 ohms = 50 mA

This is 50 mA / 5 = 10 mA current per LED.

Step 3: Attach the Circuit

I attached the circuit to the motor gear wheel with metal wire:

Step 4: Put Inside the Plastic Bucket

I placed the circuit inside the Hummus bucket:

Step 5: Testing

Testing showed that the rotating circuit fits inside the 1 kg Hummus bucket:

This is the video:

Conclusion

Now you can make the ambulance siren.

Plastic Bottle Submarine

This article is about a plastic bottle submarine that sinks but does not rise:

You can see that I used cheap blue tack for water insulation.

The water pump is driven by a 12 V battery.

Watch the video of the submarine:

Step 1: Make the Rectifier

Most cheap water pumps cannot pump in reverse. If you switch the electrical polarity then you will damage the water pump. This is why you need to make a diode rectifier. I made the rectifier with a Schottky diode that has a low forward bias voltage.

However, you do not need a Schottky diode because most water pumps need between 5 V and 12 V input, making the 0.7 V voltage drop almost irrelevant. Thus you can use a normal diode. You can order a 5 V pump with a USB plug thus eliminating the need of building the rectifier. Do not exceed the maximum input voltage of the water pump.

Step 2: Attach the Pump and Drill the Hole

Your hose must fit the hole of the water pump. Thus you will need to order hoses (to see which one fits) of a few sizes and this can cost money. If you are using more than one bottle then you will need a fitting.

I made a hole with a hole puncher.

You can also use a soldering iron.

Step 3: Testing

You can see that the water exits the bottle through the hole at high pressure:

Conclusion

If you want more challenges then you can make a submarine with more plastic bottles. 

Click on this link: https://basic-mechanics.blogspot.com