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Requirements for Bi-Level Refurb Contract ELCU: Flasher Signal On Duration must be > 0.001 seconds and < 3 seconds
Proposed Circuit Fix to accommodate ELCU signal requirements:
Circuit Signal On Duration: ~ 1 seconds +- 0.1 Second
Current Circuit Reset Duration: > 0.1 Seconds
2.1 Changes-Upgrades to Flasher Switch Signal Fix since 2.0
Positive Upgrades for 2.1
1. Made more easily implemented on Bi-Level Car Wiring -
2.1 is a 4 wire connection (2.0 had a 5 wire connection)
Car Positive
Car Negative
Input signal (Signal that originally went into ELCU IO)
Output Signal (Corrected Signal to go to ELCU IO)
2.0 needed the input signal as a close between two wires (or a dedicated NO switch) causing a large car wiring change - 2.1 can be implemented on existing car wiring with minimal wire change.
Negative Trade-off for 2.1
1. Additional Parts Needed increasing cost and manufacturing time
2. More complicated Circuitry
3. Multiple resistor sizes complicating ordering, storing and installing of components
2.0 Changes-Upgrades of Flasher Switch Signal Fix since 1.0
Positive Upgrades for 2.0
1. Output Impendence is no longer a variable on circuit performance
2. Output Signal's rising edge and falling edge are sharper and more defined
3. Designed to have common parts, such as resistors and capacitors, to simplify ordering of parts, simplify manufacturing, and to lower cost overall assembly costs.
Negative Trade-off 2.0
1. More Components increase costs
2. Increased circuit complexity and size increase manufacturing time
3. More complicated wiring change to Car circuitry to implement
Circuit Operation:
1. Closing Switch activates High signal output for limited time determined by the "Signal On Capacitor" and "Signal On Resistor" Values
2. Switch must be released momentarily to reset signal functions
3. Switch will not continue to send a signal if the Switch is held closed
Ideal Parts Needed:
3 x 100kOhm Resistors
1 x 10kOhm Resistors
1 x 1kOhm Resistors
1 x 555 IC
2 x 10uF Capacitors
2 x N-Channel MOSFET
1 x 1nF Capacitors (Optional - 555 Control Pin can be alternatively left as a no connect Pin with potential stability issues)
Simulation Notes:
1. Output Load Impedance can be changed for testing circuit in simulation using the 3-way Switches - 1MOhm, 100Ohm, and 1kOhm
2. On the Graph - Green is Input Signal, Blue is Output Signal
3. Simulation is set for real-time, but can be slowed down
Circuit Consists of a three basic parts: Inverting One-Shot (IOS) to a Timer to a Output Driver
Explanation of Idling Circuitry
1. Circuit idles at ~8.5mA and has an Open/Null Output until a Positive Input is received to the Capacitor of the Inverting One-Shot (IOS)
Explanation of Operation when a Positive Input is received to a Inverting One-Shot (IOS)
1. The Positive Signal to the input of the IOS passes through the IOS Capacitor and immediately saturates the IOS MOSFET thus IOS has a Negative output to the 555 Timer's Trigger
2. The Positive Signal also quickly charges the IOS Capacitor through the IOS charging resister
3. Once the IOS Capacitor is charged, the IOS MOSFET no longer feels the Positive Input Signal and goes into Cut-off, and 555 Timer Trigger goes Positive as it is tied to Positive of circuit through a resistor.
4. Thus this action of the IOS creates a single Negative Pulse from a Positive Signal received for greater than a specific duration.
Alternative/simpler Explanation of 2-4 is: the Inverting One-Shot sends a Negative pulse to Trigger of 555 Timer
5. Trigger Negative at the 555 Timer Enables a Positive Output and counts approx. 1 second (duration is based on time to charge Timer Capacitor through Timer Resistor)
6. 555 Timer Positive Output Saturates MOSFET (Output Driver) allowing a Positive Signal at Circuit Output which can then be the Signal to ELCU
7. 555 Timer Capacitor charges until it reaches threshold voltage (timed duration), at which point the 555 Timer instantly discharges the 555 Timer Capacitor, and the 555 Timer Outputs Negative
8. 555 Timer Negative Output Cuts-off MOSFET (Output Driver) allowing no Signal/Null (Open) at Circuit Output which can then be the Signal to ELCU
9. The Inverting One-shot needs to discharge its capacitor to reset the IOS for another one-shot signal output to the 555 Timer. The circuit now idles at ~ 12mA while a positive Signal is still present at input.
10. Finally No Positive Signal is present at the IOS capacitor, and the IOS capacitor discharges through the IOS discharge resistor resetting the whole circuit - just perfect...
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