This Toy Intercom System Is Way Better Than A Pair Of Tin Cans And Some String

December 6, 2011 by Mike Nathan 36 Comments

toy-intercom-system

On his blog, [Kenneth Finnegan] recently showed off a replica of a fun toy he used to play with as a kid, a telephone intercom system. The setup is pretty simple, requiring little more than a pair of analog phones, a battery, and a resistor.

The phones are connected to one another using a standard telephone cable, but [Kenneth] uses a 9v battery to introduce a small bias current into the loop, allowing the speakers at either end to hear one another. He also added a small LED into the circuit so that there is a visual indication as to when both handsets are off hook.

The setup is very simple at the moment, though [Kenneth] does have some ideas in mind to enhance his intercom system. He hopes to tweak the remote phone to ring when the local phone is picked up, among other things.

Telephone technology is nothing new, but for just a few dollars (or less) your kids can be entertained for hours as [Kenneth] was way back when.

Continue reading to see a short video overview of the phone system, and be sure to share your ideas for enhancing it in the comments section.

Continue reading “This Toy Intercom System Is Way Better Than A Pair Of Tin Cans And Some String” →

Two Telescope Improvements

December 6, 2011 by Brian Benchoff 5 Comments

Despite being a college class everyone regarded as an easy ‘A,’ astronomy is very hard work. Not only do many hours go into capturing a single image, the equipment itself must be constantly monitored well into the freezing cold of night. [Jerry] sent in a few neat projects that have made his nights much more comfortable.

First up is a mod for a focus controller. The focus of a telescope changes constantly with temperature, atmospheric conditions, and especially what filter is being used. The stock USB-nSTEP focuser [Jerry] used required hard-to-find unipolar steppers, so he modded his USB-nSTEM to accept bipolars with a Pololu A4988 driver.

Next up is [Jerry]’s very impressive DIY Off-axis guider that he machined himself. An off-axis guider allows an astronomer to guide the ‘scope without having to deal with a dinky, surprisingly flexible guide scope. We’re really impressed with [Jerry]’s machine skills, but that’s what you get when you’ve got an awesome mill like his.