Build an Electric Buzzer

In my previous post, I write about how to make an electric motor. Today it's time to build an electric buzzer:

"An electronic buzzer is one of the first electronic projects that you'll typically build. The simplest variation consists of a circuit with a battery, buzzer and switch. The buzzer sounds when you close the circuit and stops when you open the circuit. This is an ideal first project because it's simple, produces a verifiable result and is safe because it doesn't require a large current. It can be completed primarily with common household items and requires only a few special purchases."

Read more: How to Build a Buzzer for a Science Project | eHow.com http://www.ehow.com/how_5305594_build-buzzer-science-project.html#ixzz2MqMQ6Jln

In miniscience.com website you can find the description to create this project.
This is a photo of the project:

Follow this steps:

Prepare the materials. Scotch tape, 3v cell battery, 5v electric buzzer, scissors, and wire snips.

Remove the shrink wrap from the buzzer. The shrink wrap is made of polymer plastic film. It shrinks tightly over the buzzer when the shrink wrap is heated. You need to remove this from the buzzer.

Use the wire snips. You need to use the wire snips when snipping the wires from the buzzer. Snip the wires about an inch from outside the base of the buzzer.Position the buzzer. After you are done snipping the wires and removing all the excess wires from the buzzer, you need to set the buzzer upside down. This is the correct position for the buzzer.

Put the battery in place. The battery needs to be placed where the wires were previously located. You need to make sure that the positive and negative ends of your battery are in line with the positive and negative sides of your buzzer.

Hold the materials in place. You can use the scotch tape to hold everything. This is to secure it in place and make sure that none of what you just assembled will move.

By following these simple steps, you can experiment at home and make your own loud electric buzzer. You can in fact use old used materials that may be available in your house. This way, you don’t need to spend much on the materials.

Adapted from: howtodothings.com

Lowest frequency radar echo from the moon

7.4075 Mhz signals from HAARP received by LWA on Oct. 28, 2007, 09:00 UTC. This figure shows the ionospheric reflections and the lunar echos of three of the more than 1400 HAARP pulses received by one of the LWA antennas in New Mexico. Credit: Naval Research Laboratory

"A team of scientists from the Naval Research Laboratory (NRL), the Air Force Research Laboratory’s (AFRL’s) Research Vehicles Directorate, Kirtland Air Force Base, N.M., and the University of New Mexico (UNM) has detected the lowest frequency radar echo from the moon ever seen with earth-based receivers."

in PhysOrg

LWA Big Blade Antenna. Credit: NRL

The lunar echo measurements at 7.4075 MHZ are believed to be the lowest frequency (longest wavelength) at which bistatic radar measurements have been conducted. "Even though lunar echoes have been detected before at higher frequencies, it was really exciting to see them arrive in real time out under the full moon in the New Mexico desert," says NRL's Hicks.

in NRL