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Wednesday, October 19, 2011
Measure resistance and capacitance without an A/D
The old "one-shot" monostable multivibrator circuit has been around since the discovery of the electron. Popular IC versions of this variable pulse width generator include the 74123 and the famous (Philips) Signetics NE555 timer. These circuits use the time to charge a capacitor to a predefined voltage as their time delay.
If the threshold voltage is 1-1/e (e is the natural log base), then the time delay in seconds is exactly the product of the resistance in ohms and the capacitance in Farads (t=RC). This is a linear equation and it can be used to measure an unknown value of R if C and t are known. The purpose of this article is to describe ways to measure a RESISTANCE by using this technique with an 80C51 type of microcontroller.
by Don Sherman AN449 - NXP Philips Application Notes
Sunday, October 16, 2011
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Thursday, October 13, 2011
LED Lighting at delabs Tech
The CFL lamps have reduced the use of the Filament Bulb due to lower power consumption. Now LED lamps may have to replace CFL but it is progressing. Few years ago only Conference Rooms, Media Events or Product Exhibits could afford the LED lighting, it was a Novelty. Now LEDs are affordable and Reliable Driver Solutions are also available.
The problem like in most Tech Learning Curves is now the SMPS drivers for these LED Arrays. The LEDs are reliable, but drive systems are still having problems. Cost effective drive systems from make affordable lighting possible. But due to Quality and Reliability issues, system integrators face implementation problems.
When Mitutoyo the maker of the Best Metric Tools started decades ago, it faced a tough market. In those days, Japanese Goods were known as cheap and low quality in Europe and America.
Companies like Mitutoyo, Sony, Misubishi, Hitachi and many more changed the scenario completely. Now Japan is a Symbol of High Quality and New technology Innovations. Other countries should follow this Golden Example set by Japan and its Products. Every new firm has to go thru those Stages.
A genuine long term commitment to R&D and Quality will build the reputation of Brands, Firms and entire Regions. Anyway, here are some nice resources to help build Drivers and Systems for LED Lighting.
These Semiconductors and Applications are Excellent, the driver systems have to be engineered and perfected by manufacturing and development. A casual or quick results method will backfire. Hence system integrators start by working closely with the vendor (Vendor Development) of Drive Systems. Finally deliver only systems that are Robust and Burnt in. The other option, work with know friendly customers as a Beta Testing and learning phase, till systems reliable for global deliveries.