Electric BMX Has Pedals That Can’t Be Pedalled

electric-bmx

We don’t mind it that there’s no chain connected to these pedals. At least there’s still somewhere to put your feet and our legs are too long to comfortably pedal this size of bike anyway. As you can tell, the added hardware takes care of locomotion using an electric motor.

The first step in this project was to find a steel bike frame to make welding a bit easier than it would be for aluminum. From there the paint was sanded at the attachment points and mounting brackets were fabricated from some angle iron. The rear mount houses a 500W 30A AC motor which uses a chain to drive the rear wheel. A specialty hub was found which allows the added sprocket to be installed on the left side of the rear wheel. Some threading issues prompted [Michael Monaghan] to come up with a method of adding a slot to lock the part in place.

Near the front fork the second mounting bracket holds the batteries; a pair of sealed lead-acid units. The speed control mounts on the top where the rider has easy access to it. The finished bike can get up to thirty miles per hour with a range of up to twenty miles between charges.

If you want your own electric bike on the cheap you can try building one from a salvaged washing machine motor.

555-timer charges lead acid batteries

555-timer-charges-lead-acid-batteries

[Kenneth Finnegan] took the focus of a great design and redirected it to solve his own problem. What results is this lead acid battery charger based on the 555 timer. It’s not a top-of-the-line, all the bells and whistles type of charger. But it gets the job done with a readily available IC and no need to code for a microcontroller.

The original idea came from a solar battery charger entered in the 555 timer contest. The main difference in application between that and [Kenneth's] application is the source. A solar array or wind turbine is limited on how much juice it can produce. But mains power can push a shocking (har-har) amount of current if you’re not paying attention. Herein lies the alterations to the circuit design. To control this he’s using a Laptop power supply as an intermediary and only implementing the constant current portion of the tradition 3-stage lead acid charging profile (those stages are explained in his write up).

He did a talk on the charger at his local radio club. You can see the 90-minute video after the break.

[Read more...]

Convert a speaker to a battery-powered amplifying party box

[Matt the Gamer] loved his pair of Minimus 7 bookshelf speakers. That is until a tragic hacking accident burned out the driver and left him with a speaker-shaped paper weight. But the defunct audio hardware has been given new life as a single portable powered speaker. Now he can grab it and go, knowing that it contains everything he needs to play back audio from a phone or iPod.

The most surprising part of the build is the battery. [Matt] went with a sealed lead-acid battery. It just barely fits through the hole for the larger speaker, and provides 12V with 1.2 mAh of capacity. He uses an 18V laptop power supply when charging the battery. The PSU is just the source, his own circuit board handles the charging via an LM317 voltage regulator. Also on the board is an amplifier built around a TDA2003A chip. He added a back panel which hosts connections for the charger and the audio input. Two switches allow the speaker to be turned on and off, and select between battery mode and charging mode. As a final touch he added a power indicator LED to the front, and a drawer pull as a carrying handle.

Motorized skateboard just begging to be your next project

You’re not going to be doing any flip-tricks with this board, but it’ll let you get around without getting sweaty. The ZBoard is a motorized skateboard which is in the pre-order stages thanks to a successful Kickstarter campaign. It’ll set you back $500 now or $600 later. With that kind of budget wouldn’t it be fun to build your own?

This base model can go about five miles or five hours between charges. It carries a seal lead-acid battery (really?) but if you upgrade to the pro model for just $250 more you get a LiFePo that doubles the range (but curiously not the run time). To make it go there are pressure sensitive foot pads on the front and rear of the deck. This allows you to go slow with just a bit of pressure, or put the pedal to the metal to get up to the 15 mph speed limit. It’s even got regenerative breaking to slow things down while giving a boost to the battery.

The idea is nothing new. But the cleanliness that this product brings to market is something to be respected. We’re hoping this sparks some inspiration for a rash of DIY clones, kind of like we’ve seen with the Segway.

[Read more...]

Electric scooter sings as it travels

This scooter has been fitted with a three-phase induction motor. It reminds us of the sound effects from vehicles in the Jetsons. Right now they’re using lead-acid batteries and get about 15 miles of range from one charge. Once they switch over to lithium polymer they calculate the range will be closer to 45 miles due to the reduced weight and increased capacity. Not bad for $600 in parts, and we’d bet it’s both faster and more stable than the one-wheeled-wonder we saw last week.

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