Arduino and DC Solid State Relay 'Flicker'

[LickMyEyeball]

Hi, thank you for your help in advance.

I have a circuit configured as shown in this image. I got this arrangement from an earlier thread.

An arduino controls a DC solid state relay, and it works fine when my load is a simple LED. The arduino is controlling through a digital output header and using the digitalWrite() function, so I don't think PWM has anything to do with it. The arduino is powered by an external source: not USB.

Making that load a motor as shown in the image causes problems though. I have an LED in series so that I can see when the relay is closed and power is being delivered. It flickers at about 4-5 Hz I would say.

My relay is the CN024.

The relay is capable of delivering up to 3.5 A at 24 VDC. It is powered by a 7 VDC switched adaptor source right now. The power source can deliver up to 2 A. It is zero-crossing.

The motor it is powering is a simple servo motor. It is rated for up to 6V and typically draws 140 mA.

Despite this, is the flickering caused by a high current inrush and the circuit is being broken by a protective circuit in the servo? Though my knowledge is limited, it seems like all the requirements have been met: the SSR circuit is being closed, and there can be enough voltage supplied and current delivered. I tried putting a diode in series in order to drop the voltage from 7 V to (7-0.6)=6.4 V just to make sure the voltage wasn't too much.

Any ideas?Code included below, if it's important:
//Servo Potentiometer Control

#include <Servo.h>

const int SERVO=10; //Servo on Pin 3
const int POT=A0; //POT on Analog Pin 0
const int RELAY=3;

Servo myServo;
int val = 0;

void setup(){
myServo.attach(SERVO);
pinMode(POT,INPUT);
pinMode(RELAY,OUTPUT);
digitalWrite(RELAY,HIGH);
Serial.begin(9600);
}

void loop()
{
val=analogRead(POT); //Read Pot
val=map(val,0,1023,0,179);//Scale it to the servo range
myServo.write(val); //Sets the servo
Serial.println(val);
delay(15);
}

 

[LickMyEyeball]

Resolved:

this issue was caused by a very bad power supply.

 

[Baluncore]

Your LED should be in parallel with the motor, not in series. You have an unnecesary series diode to the motor.
Attached is a revised circuit.

 

[LickMyEyeball]

Thank you again!

 

[jim hardy]

From servo documentation https://www.parallax.com/sites/defa...tinuous-Rotation-Servo-Documentation-v2.2.pdf

Power requirements: 4 to 6 VDC; Maximum current draw140 +/- 50 mA at 6 VDC when operating in no load conditions, 15 mA when in static state
(they don't say what is max loaded)

Power Precautions

Do not use this servo with an unregulated wall-mount supply. Such powe supplies may delivervariable voltage far above the stated voltage.

Do not power this servo through the BASIC Stamp ® Module's Vin pin, this can deliver voltages above the stated voltage. See the Board of
Education Connection Diagram below for jumper
settings.

Servo current draw can spike while under peak load; be sure your application's regulator is
prepared to supply adequate current for all servos used in combination.

good find, have fun!

 

[Baluncore]

Sorry, R1 must be moved to limit LED current, no resistor is needed with the SSR LED.
Attached revision.