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Comprehensive LED Workshop Guide - Basics, Circuits, and Soldering Techniques

This detailed workshop agenda covers the fundamental aspects of LED technology, including LED structures and circuits, calculating dropping resistors, and dual supply connections. Attendees will learn efficient soldering tips for discrete and strip diodes, and understand different configurations for club standards and voltage setups. Practical demonstrations led by C. Bartel will clarify concepts such as LED voltage drops, assembly, and circuit calculations. Essential for modelers and hobbyists looking to optimize their LED lighting projects.

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Comprehensive LED Workshop Guide - Basics, Circuits, and Soldering Techniques

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  1. LED WorkshopOctober 19,2011

  2. Agenda • Basic LED structure & circuits • Strip LED structure • Calculating dropping Resistor • Dual Supply connections • Soldering Tips – discrete diodes • Soldering Tips – strip diodes • “Club” model voltages • Proposed Club standard • Demonstration C. Bartel

  3. LED Basics • An LED is a diode with light emitting capability when powered with a dc voltage. • Semiconductor chip is very small compared to the size of the package. C. Bartel

  4. Options in LED Packages • Lens – point or diffused • Color (of interest for rr models) – red, yellow, green, white • Two color – polarity reversal changes color – red/green • Three color – polarity reversal or ac provides three different colors – red/green/yellow • LEDs with integrated IC – blinking (aircraft warning lights?) C. Bartel

  5. Voltage Drops • Standard diode  0.8 volts • Red LED  1.63 < V < 2.03 • Yellow LED  2.03 < V < 2.10 • Green LED 1.9 < V < 4.0 C. Bartel

  6. Critical Factors • Determine Delta Voltage drop from spec sheet • Use mid range value color • Determine Current Range • Use less than spec current for protection • Excessive current creates heat, heat kills die • Subtract Delta drop from power supply • Divide this voltage by the current • Provides resistor value to achieve spec current C. Bartel

  7. Standard Resistor Values • 100 220 470 • 120 270 560 • 150 330 680 • 180 390 820 • 100 to 820 ohms • Multiple by 10 to get 1,000 to 8,200 • Multiple by 100 to get 10,000 (10k) to 82 ,000 (82 k) • Multiple by 1000 to get 100K through 820K • 10% values – available from Radio Shack C. Bartel

  8. Non Standard Values • Parallel resisters • RT = R1*R2/(R1+R2) • Series resisters • RT = R1+R2 C. Bartel

  9. Current Calculation • Resistors rated in watts • Multiple current X voltage across resistor • ¼ watt, ½ watt, 1 watt & higher • 1/8 watt too small- do not use • Higher wattage (5, 10, 25) are sealed and screwed to a heat sink • Select smallest wattage possible (packaging) C. Bartel

  10. Circuits using discrete LEDs • LED in parallel have limitations • Better in series C. Bartel

  11. Calculations • Parallel • Use diodes with same drop • Add currents for each diode • Calculate dropping resister • Series • Use lowest value of peak current of the leds • Add up total delta voltages, subtract from supply • Divide voltage drop by selected current, select resistor C. Bartel

  12. LED assemblies • LED Strips rated for specific operating voltage • Optimizes output light versus life • Has an operation range • For club strips, 12 v rated, operate to about 7 volts • Components are surface mounted • Includes dropping resistor to limit current C. Bartel

  13. Dual Supplies • Based on LED strips • Rated for 12 vdc, highest lumens output • Visible in building light (Fair display, Gardens) • If used on home layout without power distribution • Use 9 vdc transistor battery • Each 3 LEDs draw about 17 ma • Duracell 9 volt batter rated 800 ma hours • Estimated hours of operation: 40 hours C. Bartel

  14. Battery Performance C. Bartel

  15. Dual Supplies • If setting up model for dual operation • Install batter holder (Radio Shack heavy duty 9 volt snap connector – in stock) • Connect to terminal strip C. Bartel

  16. Using LED lights to Set Time • Split model into zones • Day zones • Business, public places • Dusk zones • Houses, apartments above stores • Night zones • Bedroom areas, 24 hr factories, public areas (train stations, eating facilities, gas stations) C. Bartel

  17. Using LED lights to Set Time • Terminal strip • Common ground • Hot terminal for zone 1 • Hot terminal for zone 2 • Hot terminal for zone 3 • Hot terminal for “24’ Hour lights C. Bartel

  18. Soldering Tips • Individual diodes • Use heat sink to protect die (alligator clip works) • Use low wattage iron if available • Use electronic solder • Tin supply wire • Clean resistor and led lead wires if discolored • Mechanical joint first, than solder C. Bartel

  19. Soldering Tips • LED strips • Strips are “flexible” Printed Wiring Board (PWB) • Strips have adhesive on back • Recommend not adhering to metal plate • PWB is double sided, plated through holes • PWB has solder mask for production soldering, do not remove • Do not open holes for wire, use # 20 or smaller to terminal strips (opening holes cuts the plating) C. Bartel

  20. “Club” voltages • Donated power supply for model lighting & sound systems • Voltages available: + 12 Vdc 20 amps + 5.0 Vdc 30 amps + 3.3 Vdc 5 amps • 5.0 Vdc • 12 Vdc C. Bartel

  21. Proposed Club Standard • All lighting be rated at 12 Vdc or 5 Vdc • All ground wires be brown • + 12 Vdc be gray wire • + 5 Vdc be violet wire • + 3.3 Vdc be blue wire • Model terminal strip be marked Grd (-), Zone 1 through Zone 3 and/or 24 hr C. Bartel

  22. Demonstration • 12 vdc versus 9 volt battery • Zone 1 and 2 example • Single point source LED • Blinking led C. Bartel

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