Add $91 cost/year per 100W of internal server

For low consumption levels (<15MWh per month), midwest electricity prices out at 10.36/hr. Therefore, when calculating the relative cost of hosting a server 24/7/365.25 internally vs in the cloud you ought to add at least $90.82/year per 100W worth of internally hosted server, where that 100W must include UPS and cooling inefficiencies. Assuming a 90% UPS efficiency and HVAC COP of 3.4, that's 71W of actual server power. If your server is not designed specifically to reduce energy, expect muc...

Vertical lift: Prototypes #4, 5, 6

(See also prototypes 1 through 3.) Prototype #4: Quad-Pulley Elevator (axled) A fundamental shift in design vis-à-vis prototypes 1-3, lift #4 raises a rectangular platform via four corner pulleys. Design: 1/2" steel pipe structure. Flanges bolted to pulleys for pipe framework attachment. To minimize drive complexity, a single 12V/2000lb winch ($50, Chicago Electric model 92860) draws all four pulleys simultaneously via a pair of axles. Several additional pulleys redirect cable f...

Vertical lift: Prototypes #1, 2, 3

Objective / Constraints Automated vertical transportation. Vertical travel: 100 to 200cm. Load: 4 to 30kg. Some objects must remain at a constant orientation and cannot endure significant acceleration or jerk.  For instance, unenclosed liquids and most LCD displays cannot withstand impacts and must be oriented within a few degrees of vertical at all times. SPOILER: Of 8 prototypes, the first 7 failed in practical applications. Prototype #1: Electric scissor jacks 12VDC/6...

PCB release: Peripheral Driver

First release of PCB design: Peripheral Driver. 2 layers, 1.3x2in (33x50mm). ATmega328 (or similar) microcontroller logic at up to 20MHz clock. Eagle design files and BOM available via GitHub repository: PCB-PeripheralDriver. Each of the 22 three-pin peripheral headers provides low-voltage power, a unique microcontroller signal pin, and a common ground. Intended to manage peripherals with high current requirements and/or noisy electrical feedback: servos, relays, high-lumen lighting, act...

Motor Controller Server v0.4 (alpha, first release)

An integrated Motor Controller Server (MCS), running under MapOS.  In addition to the standard MapOS dynamic routing capabilities, the AVR version of the MCS sports a continuous oscilloscope output [ADCServer from the ATcommon library], analog encoder sensor monitoring [with fixed-point position output], a PID engine with realtime coefficient configuration, and an ESC control server [PWM output]. An earlier version of this server was fielded in ATR5-b1.  (The fires were not the server's f...

Meanwell S-350-12 12VDC power supply

ATX power supplies, as are found in most PCs and cheaply on eBay, shutdown in the event of a current overload (or short circuit) until the 120VAC input is power cycled (disconnected and reconnected). This is a reasonable response in the context of sensitive motherboard components. However, some AT units (e.g. ATR5) carry large inductive loads (kilowatt DC motors) which instantly kill ATX supplies due to their spin-up current surges. The Meanwell S-350-12 switching power supply resembles a...

High Current DC Connectors

Small diameter barrel connectors (1- to 2-pole, different sizes incompatible) are the ubiquitous low-current DC connector, supplying up to 2A.  USB Mini-B connectors supply only about 1.5A max (plenty for logic!), whereas reliable but bulky Molex connectors (2- to 26-pole) can handle 5A.  SAE 2-pole connectors can handle at least 5A, and are hermaphroditic (which simplifies charging, for instance). Servos often use a 3-pin connector, 26- to 22-gauge, where the third wire is a low-current signal ...