- Making a tachometer for a grinding / polishing machine for telescope mirrors
- Massive scalability when querying metrics stored in Graphite
- multifactor authentication for distributed VPN mesh - part 3, VPN mesh
- multifactor authentication for distributed VPN mesh - part 2, token configuration, local OTP
- multifactor authentication for distributed VPN mesh - part 1, server and client configuration, cloud OTP
- Easy multifactor authentication for SSH using YubiKey NEO tokens
- Monitoring for the cloud, part 2 - architecture
- Monitoring for the cloud, part 1 - tools and techniques
- 150 mm f/8 mirror (25 mm Pyrex) Polishing and figuring log
- How to see Sirius B
When making a telescope mirror on the machine, two parameters are important: the rotation speed of the mirror, and the rotation speed of the overarm eccentric. Other environmental parameters also matter: temperature and humidity are foremost here. To more easily monitor and display these variables, I've built an electronic device that collects this data and shows it on the control panel. This is how to build the device.
It used to be that lasers were big bulky expensive things that required a laboratory to run and an entire factory to build. I remember the first He-Ne laser I saw two decades ago, the size of a small telescope and probably not more powerful than the laser pointer I carry on the keychain nowadays. Well, not anymore. It's pretty easy to build a laser today, on the kitchen table or in the garage, for a surprisingly small investment. The goal is to make a laser capable of burning small objects, such as a piece of paper, a balloon, etc, while keeping the whole project cheap - even as cheap as $35 if you don't make any mistakes. Here's how.