Hobby Projects - Insulation tester, LED Circuits, Meters.

Friday, November 18, 2011

Microohm Meter with LED Analog Bar

This indicates like LM3914 in dot-mode. It is a drawing i made made to troubleshoot a gadget, around two decades ago. Strangely it had a echo of a design i had made into a 7107 dpm years before that. Now i am scanning all my drawing and notes, useful or not. Clean or with errors. Many Errors = 1 Blunder. Some projects i made have been expensive Blunders. So see them with a skeptic eye, fix them, try them. Thats all for now.

See the Circuit Full Size - Microohm Meter with LED Analog Bar

Microohm Meter with LED Analog Bar

This has a 9V battery power. The 555 spins and a negative voltage for Opamp is created. This is a Low Offset amp of OP37 of Precision Monolithics, Inc PMI an early innovator. This diff-amp amplifies the uV of a 4 wire resistance measurement.

Now the current pump is the 2N2222 you see above the OP37. The FET and 555 do synchronous rectification. The LM324 is the Indicator and Analog to LED Dot-Bar Converter. The probes are Gold Plated, or use solid gold pins if you have them in plenty.

Thursday, November 17, 2011

Embedded 8051 TCP-IP WebServer

Web51 is a complex project of connecting an Intel x51 compatible processor to a Realtek RTL8019AS network controller. The result is a very low-cost Ethernet interface. Since a well-known x51 architecture is used, even small and medium-scale businesses can now network their devices.

Project is free. Almost all source codes are available.

Web51 - Project start page

Charon module

Charon module

Twisted Pair Ethernet 10 Mbit 802.3,Serial TTL level compatible line RS232 (RxD, TxD, RTS, CTS), 32 kB RAM, 64 kB FLASH, 2kB EEPROM.

Murray's Website is missing so here are the related resources.

Embedded 8051 TCP-IP WebServer 

ET have produced a remarkable board in the WEB51. It is based on the popular Atmel AT89C51RD2 microcontroller, and features the RealTek RTL8019AS full-duplex ethernet controller chip.

You get a huge 64K In-System-Programmable FLASH memory for code and web content, backed up by up to a further 4 optional, I2C addressable EEPROM memory chips.

The ET-WEB51 TCP/IP Ethernet Web Control Board comes preloaded with TCP/IP software that allows you to control outputs, sense inputs and write text to an LCD. All this across the Internet via a standard browser.

"From controlling appliances on your home network, to monitoring industrial processes on the other side of the Earth, the ET-WEB51 can do it all."

Embedded 8051 TCP-IP WebServer

littleBits – Snip Snap and Build Electronics

littleBits is a growing library of pre-assembled circuit boards that snap together with tiny magnets!

littleBits - Snip Snap and Build Electronics

littleBits are simple, intuitive, space-sensitive blocks that make prototyping with sophisticated electronics a matter of snapping small magnets together. Each bit has a simple, unique function (light, sound, sensors, buttons, thresholds, pulse, motors, etc), and modules snap to make larger circuits.

My Notes -

A kid started with "Meccano Set" in the early days. Then there came "The LEGO" now we have littleBits doing it for DIY Electronics Learning. Shown below is a Meccano Kit.

Meccano set

Thursday, November 10, 2011

mbed - Rapid uC Prototyping

The mbed Microcontroller is made for prototyping, and comes in a 40-pin 0.1" pitch DIP form-factor so it's ideal for experimenting on breadboard, stripboard and PCBs. It is a uC ScratchPad for trying out new ideas.

mbed - Rapid uC Prototyping

From Hyper Embedded - Microcontroller ASIC and EDA

The mbed Compiler lets you write programs in C++, and then compile and download them to run on the mbed Microcontroller. The mbed Compiler is a Web-App in the Cloud, you don't have to install or setup anything to ignite your first mbed project idea. Any OS, Any Where, your software is online and ready to use. You will need a computer or netbook with a Browser.

Two XBees and One USB Explorer

"I had two XBee modules that I really wanted to use with the mbed. These are the standard OEM RF Modules one with an antenna and one with a ANT chip. For one of the chips I will be using the Xbee Explorer USB from Sparkfun...."