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edits
User talk:Daveb: Difference between revisions
From London Hackspace Wiki
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I wonder how the users of SMD packages manage it? | I wonder how the users of SMD packages manage it? | ||
== rough design == | |||
* dynamo->AC | |||
* AC->2 crossed 5% 19V zener diodes to clip(+/- 5% -> 18 to 20V output) to safe range of rest of system | |||
* AC->diode bridge->DC (using 10-15V diodes, loose .5V so 17.5 to 19.5 max V) | |||
* (three of)DC->LED strings->logic level 20V mosfets->GND | |||
* DC->2.5V reg->Vcc->MCU->GND (requires DC >= 2.8V) | |||
* AC->diode-> 100k resister-(MCU int0 pin)->2.5V zener diode->GND | |||
* MCU_reset->Reset_debugWire->100k resistor->Vcc | |||
* MCU_[3*gpios]->MOSFET Gates | |||
* MCU_[gpio]->light sensor | |||
* DC->prog supply pin | |||
* Vcc->Vref_debugWire | |||
* Gnd->Gnd_debugWire | |||
NOTES | |||
If the LEDs light up below 2.8V, then I need to think about lower voltage supply for MCU. | |||
One LED string should default to ON - so that while the MCU is booting there is a power consumer to stop capacitors charging to unsafe voltages. | |||
Not sure what the failure modes are and what protection should be added. | |||
Plans for cooling of LEDs are still vaugue. | |||
