EK010 Voltage Controlled PWM Generator
Part.no: 41015617
EK010 consists of a simple oscillator built around an operational amplifier. The oscillator provides two simultaneous outputs for triangle and square wave signals with adjustable duty cycle from 0 to 100%.
The duty cycle can be adjusted using the potentiometer on the board or with an external control voltage between 0 and 10V. To limit the adjustment range of the potentiometer, resistors R10 and R11 can be replaced with resistors of higher resistance.
The frequency is adjustable from 300Hz to 3kHz. For a wider frequency range, the potentiometer can be changed from 100kohm to 1Mohm. To shift the frequency range up or down, capacitor C1 can be replaced with a capacitor of lower or higher capacitance.
The outputs are protected with 1kohm resistors, which also define the output impedance. These resistors allow the outputs to be short-circuited to ground indefinitely and enable them to drive capacitive loads.
EK010 is not suitable for driving heavy loads directly, but can be combined with EK010b to drive, for example, small DC motors, solenoids, or LEDs.
To use EK010 as an audio signal generator, a capacitor should be connected in series with the output to eliminate the DC offset and center the signal around 0V.
- Supply voltage: 12-24VDC
- Current draw: 10mA (@12V)
- Frequency range: 300Hz – 3kHz
- Pulsewidth: 0 – 100%
- External control voltage: 0 – 10V (12V supply voltage)
- Dimensions 45.72 x 40.64mm
- Mounting holes: c-c 40.64 x 35.56mm, ø2.54mm
Component list
| RefDes | Value | Qty. | Part.no. | Marking |
|---|---|---|---|---|
| HDR | Pin header 2.54mm 2-pin | 4 | 41001167 | |
| C1 (Ct) | Ceramic 10nF | 1 | 41011998 | 103 |
| C2, C3, C4 | Ceramic 100nF | 4 | 41003038 | 104 |
| C5 | El.lyt 10uF | 1 | 40520003 | 10uF |
| D1, D2 | Diode BAT42 | 2 | 40311042 | |
| D3 | LED 3mm grön | 1 | 40307003 | |
| R1, R3, R5, R6 | Resistor 10kohm | 4 | 40811410 | |
| R2, R9, R12 | Resistor 1kohm | 3 | 40811310 | |
| R4 | Resistor 8.2kohm | 1 | 40811382 | |
| R7 | Resistor 220kohm | 1 | 40811522 | |
| R8 | Resistor 100kohm | 1 | 40811510 | |
| R10, R11 | Resistor 2.2kohm | 2 | 40811322 | |
| U1 | OP amp TL074 | 1 | 40350074 | TL074CN |
| DIL socket 14-pin | 1 | 40410014 | ||
| VR1, VR2 | Potentiometer 100kohm | 2 | 41017263 | B100k |
Assembly guide
Before starting assembly, check that the PCB is free from damage and scratches. Verify that all components to be assembled are present, compare with the component list.
It is usually easiest to start assembling the lowest profile components and work upwards in size. IC sockets, resistors, ceramic capacitors and diodes are mounted first. Electrolytic capacitors, connectors and potentiometers are mounted last.
For some components, correct orientation is important. Pay attention to the markings on the PCB.
Interactive assembly guide ↗
Using
When the board is powered with 12-24VDC, the oscillator will start and output a square wave on the connection marked PWOut and a triangle wave on TriOut.
The connections marked Ext.PW can be used to control the duty cycle of PWOut. The control voltage is 0-10V at 12V supply or 0-22V at 24V supply. A higher voltage results in a wider duty cycle and a lower voltage results in a narrower one.
The duty cycle can also be adjusted using the left potentiometer.
The right potentiometer sets the oscillator frequency. The range is approximately 300Hz to 3kHz.
The outputs are buffered by the operational amplifier and can drive a load of approximately 10mA. If more drive capability is required, for example to dim LEDs or control the speed of a DC motor, the add-on board EK010b can be mounted on top to increase the drive capability of the PWM output to several amperes.
Simulation ↗
Schematic
Drawing
