In this edition of the BEST newsletter we pleased to tell you about some capabilities that our firm has developed as a response to your needs in the area of testing and reverse logistics.
We are also pleased to announce that BEST has won the Circuits Assembly's Service Excellence Award -our 2nd year running!!!!
BEST Video Soldering Tips
BEST Instructors have put together video demonstrations of common hand soldering tips and skills. These are not designed to be in place of live one on one training where repetitive skills and subsequent one on one feedback is given. Rather, they are quick refreshers designed to be viewed if a specific skill has not been practiced in a while.
Electronics Repair and Complete Reverse Logistics
BEST offers the OEM the following "back end" services:
BEST's Test and Repair Service Depot is your answer for circuit board repair and PCB Testing. We specialize in providing a quality outsource solution for PCB Testing and Board Repair to the industrial, communications, computer and medical industries..
Now for how to make 15 milliamps flow through the LED:
First you need to know the LED voltage drop. It is safe enough to assume 1.7 volts for non-high-brightness red, 1.9 volts for high-brightness, high-efficiency and low-current red, and 2 volts for orange and yellow, and 2.1 volts for green. Assume 3.4 volts for bright white, bright non-yellowish green, and most blue types. Assume 4.6 volts for 430 nM bright blue types such as Everbright and Radio Shack. Design for 12 milliamps for the 3.4 volt types and 10 milliamps for the 430 nM blue.
Next, know your supply voltage. It should be well above the LED voltage for reliable, stable LED operation. Use at least 3 volts for the lower voltage types, 4.5 volts for the 3.4 volt types, and 6 volts for the 430 nM blue.
The next step is to divide the dropped voltage by the LED current to get the value of the dropping resistor. If you divide volts by amps, you get the resistor value in ohms.
For example let's use the following vlaues : 6 volt supply, 3.4 volt LED, 12 milliamps. Subtract the 3.4 volt LED voltage from the 6 volt supply voltage to get a difference (which is across the "dropping resistor") of 2.6 volts. Divide 2.6 by .012. This gives 217 ohms. The nearest standard resistor value is 220 ohms.
One more thing to do is to check the resistor wattage. Multiply the dropped voltage by the LED current to get the wattage being dissipated in the resistor. Example: 2.6 volts times .03 amp (30 milliamps) is .078 watt. For good reliability, I recommend not exceeding 60 percent of the wattage rating of the resistor. A 1/4 watt resistor can easily handle .078 watt.
You can put LEDs in series with only one resistor for the whole series string. Add up the voltages of all the LEDs in the series string. This should not exceed 80 percent of the supply voltage if you want good stability and predictable current consumption. The dropped voltage will then be the supply voltage minus the total voltage of the LEDs in the series string.
|TABLE OF CONTENTS|
|Electronics Test and Repair|
|BEST Capabilities Video|
|Proto Assembly Estimator|
|ASK THE EXPERT|
BEST's "Ask the Expert" column is designed to give one-one dialogue between a questioner and our master instructor Kris Roberson. Specification, processing and inspection questions are asked and answered here.
|PRODUCTS & SERVICES|
|In order to contact customer care on a specific repair project click here |
BEST INDUSTRY FORUMS
This Industry forum is a discussion area where opninons are given on equipment and processes, help is goven on process problems and resources for proble-solving and troubleshooting are shared.
|WISCONSIN SMTA CHAPTER MEETING |
The Wisconsin SMTA chapter will be holding a tour and chapter meeting near Madison, WI on Thursday May 8 beginning at 10:30AM. After the tour Steve Martell from Sonoscan will be discussing proper moisture handling of PWBs and passives for lead free process. . More info here.
See an interview of BEST Inc-IPC Technology Award Recipient
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|SEE Interview of BEST at APEX |
See the interview of BEST commenting on it being the recipient of an IPC technology award