Truck-Compatible Analog Control Module
Budget: $30 – $250 USD
Project Specification
Output Voltage Control – Version 1.0
Environment: Automotive / Truck (12 V – 32 V systems, high-voltage transients)
Type: Analog control module with two independent adjustable outputs
1. General Description
The Output Voltage Control module is a dual-channel analog controller designed for use in truck and heavy-vehicle electrical systems.
It allows two independent analog outputs (OUT1, OUT2) to operate in one of two modes, controlled by a trigger input:
Bypass Mode (Trigger OFF): Inputs (IN1, IN2) are routed directly to outputs through the relay’s normally closed (NC) contacts.
Control Mode (Trigger ON): Inputs are routed through two independent potentiometers (POT1 and POT2) via the relay’s normally open (NO) contacts, allowing adjustable output voltage or signal level per channel.
The design uses a single DPDT (Double Pole Double Throw) automotive-grade relay to switch both channels simultaneously and safely within harsh vehicle electrical environments.
2. Electrical Characteristics
Parameter Specification
Supply Voltage Range (VIN) 10 V – 32 V DC
Operating Environment Automotive / Truck electrical system
Voltage Spikes / Jump-Start Protection Must withstand transient surges up to 60 V (load dump / jump-start event)
Reverse Polarity Protection Integrated MOSFET or Schottky diode protection
Input Channels 2 × Analog inputs (IN1, IN2)
Output Channels 2 × Analog outputs (OUT1, OUT2)
Trigger Input 1 × Ground trigger (active low)
Relay Type DPDT sealed automotive relay
Relay Coil Voltage 12 V nominal (driver circuit allows operation from 10 V – 32 V)
Potentiometers 2 × Independent 10 kΩ linear pots (adjust each output separately)
Cutoff & Load Ratings Defined by relay contacts and potentiometer power rating
Operating Temperature −40 °C to +85 °C
PCB Power Connector 2-pin (VIN, GND) automotive-grade terminal
Signal Connector 7-pin header: IN1, IN2, OUT1, OUT2, TRIG, VIN, GND
3. Functional Behavior
Trigger OFF (Low)
Relay unpowered → contacts in NC position.
Path:
IN1 → OUT1 (direct connection)
IN2 → OUT2 (direct connection)
Both potentiometers bypassed (no voltage drop).
Trigger ON (Active)
Relay energized → contacts in NO position.
Path:
IN1 → POT1 → OUT1
IN2 → POT2 → OUT2
Each potentiometer independently adjusts the output voltage or analog signal level.
This behavior provides precise, per-channel manual control while maintaining synchronous relay switching for both channels.
4. Power Supply & Protection System
Designed specifically for truck power systems (10–32 V) with unstable voltage conditions and transient events:
Protection Element Purpose
TVS Diode (SMCJ33A or higher) Clamps transient spikes and load-dump voltages up to 60 V
Input Fuse (1 A – 2 A automotive rated) Protects PCB and wiring from overcurrent
Reverse Polarity MOSFET (P-channel or ideal diode) Protects against accidental reverse battery connection
Input Filter Capacitors (100 µF + 100 nF) Suppresses input noise and stabilizes VIN
Relay Coil Flyback Diode (1N5819) Protects MOSFET driver from inductive voltage spikes
Optional TVS on Trigger Input Prevents false activation due to EMI
Wide Ground Plane Minimizes EMI and provides stable reference for analog control
The power section must tolerate load dumps, alternator ripple, and voltage spikes commonly found when the truck is jump-started or operating with poor battery regulation.
5. Component Specifications
Component Recommended Specification
Relay DPDT automotive sealed relay, ≥ 30 V DC, ≥ 5 A contact rating per pole (e.g., TE Connectivity, Omron G8HE series)
Potentiometers 10 kΩ linear, 0.25 W (signal-level control) or power-type if series mode is required; each pot controls its own channel
MOSFET Driver N-channel logic-level MOSFET (e.g., AO3400A, IRLZ44N) with pull-down resistor (100 kΩ)
TVS Diode 36 V standoff, 600 W minimum (e.g., SMBJ36A)
Fuse 1 A automotive blade or inline fuse
Connectors Automotive locking type or 7-pin Molex MicroFit for signal lines
6. PCB Layout Guidelines
Keep relay close to input/output connectors to minimize high-current path length.
Separate analog (potentiometer) traces from power/relay coil paths to reduce noise.
Use star-ground topology — all grounds converge near the VIN input.
Ensure wide copper traces for relay contacts (≥ 1 mm for 1 A, ≥ 2 mm for 3 A).
Place TVS diode and input filter capacitors physically close to the VIN terminal.
Include test pads for relay coil, trigger input, and each output for diagnostics.
7. Verification & Test Procedures
Test Expected Result
Power Input Test (10–32 V) Module operates correctly throughout voltage range
Load Dump Simulation (60 V, 100 ms) TVS diode clamps; relay and components undamaged
Reverse Polarity Test No current flow, circuit protected
Trigger OFF Path Test IN1 = OUT1 and IN2 = OUT2 continuity verified
Trigger ON Path Test IN1 passes through POT1; OUT1 voltage varies smoothly with adjustment; same for channel 2
Independence Test Adjusting POT1 affects only OUT1; adjusting POT2 affects only OUT2
Thermal Test No component exceeds rated temperature during continuous use
Relay Lifecycle Test ≥ 100,000 operations under nominal load without contact degradation
8. Optional Enhancements
Status LED: Indicates when relay (trigger ON) is active.
Calibration Pads: Test points before and after each potentiometer.
Input/Output Filtering: 100 nF caps for noise suppression.
Enclosure: ABS or aluminum case with ventilation and automotive mounting tabs.
9. Summary of Key Features
10–32 V DC power input (truck-compatible)
Tolerant to voltage surges, spikes, and jump-start conditions
2 completely independent analog channels
1 DPDT automotive relay for synchronous switching
Reverse polarity, overvoltage, and transient protection
Compact PCB layout for vehicle installation
Modular design for analog voltage or signal control applications
Output Voltage Control – Version 1.0
Environment: Automotive / Truck (12 V – 32 V systems, high-voltage transients)
Type: Analog control module with two independent adjustable outputs
1. General Description
The Output Voltage Control module is a dual-channel analog controller designed for use in truck and heavy-vehicle electrical systems.
It allows two independent analog outputs (OUT1, OUT2) to operate in one of two modes, controlled by a trigger input:
Bypass Mode (Trigger OFF): Inputs (IN1, IN2) are routed directly to outputs through the relay’s normally closed (NC) contacts.
Control Mode (Trigger ON): Inputs are routed through two independent potentiometers (POT1 and POT2) via the relay’s normally open (NO) contacts, allowing adjustable output voltage or signal level per channel.
The design uses a single DPDT (Double Pole Double Throw) automotive-grade relay to switch both channels simultaneously and safely within harsh vehicle electrical environments.
2. Electrical Characteristics
Parameter Specification
Supply Voltage Range (VIN) 10 V – 32 V DC
Operating Environment Automotive / Truck electrical system
Voltage Spikes / Jump-Start Protection Must withstand transient surges up to 60 V (load dump / jump-start event)
Reverse Polarity Protection Integrated MOSFET or Schottky diode protection
Input Channels 2 × Analog inputs (IN1, IN2)
Output Channels 2 × Analog outputs (OUT1, OUT2)
Trigger Input 1 × Ground trigger (active low)
Relay Type DPDT sealed automotive relay
Relay Coil Voltage 12 V nominal (driver circuit allows operation from 10 V – 32 V)
Potentiometers 2 × Independent 10 kΩ linear pots (adjust each output separately)
Cutoff & Load Ratings Defined by relay contacts and potentiometer power rating
Operating Temperature −40 °C to +85 °C
PCB Power Connector 2-pin (VIN, GND) automotive-grade terminal
Signal Connector 7-pin header: IN1, IN2, OUT1, OUT2, TRIG, VIN, GND
3. Functional Behavior
Trigger OFF (Low)
Relay unpowered → contacts in NC position.
Path:
IN1 → OUT1 (direct connection)
IN2 → OUT2 (direct connection)
Both potentiometers bypassed (no voltage drop).
Trigger ON (Active)
Relay energized → contacts in NO position.
Path:
IN1 → POT1 → OUT1
IN2 → POT2 → OUT2
Each potentiometer independently adjusts the output voltage or analog signal level.
This behavior provides precise, per-channel manual control while maintaining synchronous relay switching for both channels.
4. Power Supply & Protection System
Designed specifically for truck power systems (10–32 V) with unstable voltage conditions and transient events:
Protection Element Purpose
TVS Diode (SMCJ33A or higher) Clamps transient spikes and load-dump voltages up to 60 V
Input Fuse (1 A – 2 A automotive rated) Protects PCB and wiring from overcurrent
Reverse Polarity MOSFET (P-channel or ideal diode) Protects against accidental reverse battery connection
Input Filter Capacitors (100 µF + 100 nF) Suppresses input noise and stabilizes VIN
Relay Coil Flyback Diode (1N5819) Protects MOSFET driver from inductive voltage spikes
Optional TVS on Trigger Input Prevents false activation due to EMI
Wide Ground Plane Minimizes EMI and provides stable reference for analog control
The power section must tolerate load dumps, alternator ripple, and voltage spikes commonly found when the truck is jump-started or operating with poor battery regulation.
5. Component Specifications
Component Recommended Specification
Relay DPDT automotive sealed relay, ≥ 30 V DC, ≥ 5 A contact rating per pole (e.g., TE Connectivity, Omron G8HE series)
Potentiometers 10 kΩ linear, 0.25 W (signal-level control) or power-type if series mode is required; each pot controls its own channel
MOSFET Driver N-channel logic-level MOSFET (e.g., AO3400A, IRLZ44N) with pull-down resistor (100 kΩ)
TVS Diode 36 V standoff, 600 W minimum (e.g., SMBJ36A)
Fuse 1 A automotive blade or inline fuse
Connectors Automotive locking type or 7-pin Molex MicroFit for signal lines
6. PCB Layout Guidelines
Keep relay close to input/output connectors to minimize high-current path length.
Separate analog (potentiometer) traces from power/relay coil paths to reduce noise.
Use star-ground topology — all grounds converge near the VIN input.
Ensure wide copper traces for relay contacts (≥ 1 mm for 1 A, ≥ 2 mm for 3 A).
Place TVS diode and input filter capacitors physically close to the VIN terminal.
Include test pads for relay coil, trigger input, and each output for diagnostics.
7. Verification & Test Procedures
Test Expected Result
Power Input Test (10–32 V) Module operates correctly throughout voltage range
Load Dump Simulation (60 V, 100 ms) TVS diode clamps; relay and components undamaged
Reverse Polarity Test No current flow, circuit protected
Trigger OFF Path Test IN1 = OUT1 and IN2 = OUT2 continuity verified
Trigger ON Path Test IN1 passes through POT1; OUT1 voltage varies smoothly with adjustment; same for channel 2
Independence Test Adjusting POT1 affects only OUT1; adjusting POT2 affects only OUT2
Thermal Test No component exceeds rated temperature during continuous use
Relay Lifecycle Test ≥ 100,000 operations under nominal load without contact degradation
8. Optional Enhancements
Status LED: Indicates when relay (trigger ON) is active.
Calibration Pads: Test points before and after each potentiometer.
Input/Output Filtering: 100 nF caps for noise suppression.
Enclosure: ABS or aluminum case with ventilation and automotive mounting tabs.
9. Summary of Key Features
10–32 V DC power input (truck-compatible)
Tolerant to voltage surges, spikes, and jump-start conditions
2 completely independent analog channels
1 DPDT automotive relay for synchronous switching
Reverse polarity, overvoltage, and transient protection
Compact PCB layout for vehicle installation
Modular design for analog voltage or signal control applications