Posted 03.11.2010 at 4:32 pm
6 Comments
Get that Guy Ahead of You to Move It
Peter McDonnell/Linda De Moreta Represents
Here’s a project sure to head off your road rage. Instead of silently fuming the next time you’re stuck in traffic behind some attention-deficient driver who fails to move when the light turns green, just give him a friendly yet firm word of encouragement through your DIY megaphone. He’ll definitely get the message. The device projects your voice using a small microphone connected to a preamplifier and boosted with a power-amplifier circuit. It won’t deafen anyone, but it can provide a step up to more than twice your normal speaking volume. Of course, you don’t have to be on the road to use it—the megaphone comes in handy anywhere you find yourself needing to send a message loud and clear.
A Compact DIY Megaphone: Brian Klutch
Make a Compact DIY Megaphone
Time: 5 Hours
Cost: $47.01
Difficulty: Medium
Parts List
- Mic Preamp Kit – (SparkFun Electronics #PRT-08872; $2.95) NOTE: this kit must be built from separately-purchased components; approx. $5.00 extra.
- LM1877 (Digi-Key #LM1877M-9-ND; $1.64)
- 3-100K resistors (Digi-Key #CF1/4100KJRCT-ND; $0.24)
- 2-1.8K resistors (Digi-Key #CF1/41.8KJRCT-ND; $0.24)
- 1M potentiometer (Digi-Key #3306F-105-ND; $0.71)
- .1mF ceramic capacitor (Digi-Key #399-4454-1-ND; $0.13)
- 2-4.7mF electrolytic capacitors (Digi-Key #493-1056-ND; $0.36)
- 220mF electrolytic capacitor (Digi-Key #565-3062-ND; $0.98)
- .47mF electrolytic capacitor (Digi-Key #P13474-ND; $0.11)
- 9V battery (RadioShack #23-1123; $5.49)
- 9V battery clip (RadioShack #270-0325; $1.99)
- 8-“AA” batteries (RadioShack #230-1127; $8.99)
- 8AA battery holder (RadioShack #270-0387; $1.99)
- 2-SPST momentary switches (Digi-Key #509PB-ND; $2.82)
- Project box (Digi-Key # SRH67-9VG-ND; $8.32)
- 8-ohm 2W speaker (Digi-Key #668-1191-ND; $4.81)
1. Download our schematic circuit diagram. Assemble the mic preamp kit [A] per the instructions on www.sparkfun.com/categories.php.
2. Build the power amplifier [B], which combines the output of the two two-watt channels that are inside the integrated circuit.
3. Connect the nine-volt-battery clip’s black lead to the mic preamp’s GND pin, and its red lead to one SPST switch [C]. Wire the second pole of the SPST switch to the on/off pin for the mic preamp kit. Pressing this switch will activate the microphone.
4. Wire the positive lead from the eight-AA-battery holder’s clip to the second SPST switch [D], and the negative lead to the amp’s GND pins. Attach a wire between the second pole of the switch and the 12-volt power-supply pin. Pressing this switch will fire up the amplifier.
5. Insert all the components into the project box, connect the speaker, and install fresh batteries. Press both switches simultaneously to activate the megaphone. Adjust the potentiometer for optimal voice quality and volume.
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It says that the first thing you need is the mic preamp kit, but then it also says it needs to be assembled from different parts. What are those, and do I just need to buy the mic preamp kit? Also, I cant find the instructions for the preamp kit assembly on sparkfun.com. Can you help me?
@ julyer97 The sparkfun link is down when I tried. However, just by googling the company and typing in the search box, I found the following:
www.sparkfun.com/commerce/product_info.php?products_id=8872
Probably what you are looking for is near the bottom of the page with the link marked "schematic".
Enjoy!
is illegal in most states. I got pulled over a few times for using a megaphone speaker mounted behind the grill of my Jeep. The speaker was connected to an amp for maximum decibel blast which was then connected to my CB radio. Nothing more fun than yelling at people to "Make a hole and make it wide!" when trying to get through traffic.
However, it is dangerous because you can scare the bejesus out of people pretty readily with a setup like mine. Cops just always told me to disconnect it and to not use it on public roads, just on my own property and off-roading.
For more fun with vehicle mounted amplified yelling devices see: 'Kelly's Heroes'
Everyones favorite character Oddball uses one mounted on his Sherman tank to play classical music when riding into battle and also to yell at people indiscriminately.
Good times.
--GTO--
I dont get it, what are the extra parts that you need to complete the mic preamp kit. Please help!
My redneck little brother hooked his CB radio up to a megaphone speaker of some type under the hood of his pickup truck. We could hear him singing Brooks and Dunn from a couple of miles away as he drove home.
It is probably on my list of "top ten annoying things that my little brother did," right up there with practically having a seizure every time he saw a John Deere... even when we were on the school bus- in HIGH SCHOOL. That megaphone scared the bajeebers out of me several times in the parking lot of the local grocery store when he would drive up and start yelling stupid comments at me through it.
T'is an Ill wind that blows no minds...
I'd like one for yelling "get off the freikin' phone" at persons who insist on using their cell phones while driving!