Hi,
I'm supposed to build a circuit with a transformer. It's going to take 220V mains as the input and convert it to DC in a magnitude range of 1.25V to 12V. There shouldn't be any ripples in the output signal with an input of 176V to 264V. However my circuit starts to ripple around 230V when the input rms value is decreased from 264V. Also I cannot have steady display of the output signal on an oscilloscope. It vibrates up and down. When I try to measure it with a digital voltmeter it again won't give a distinct result. It keeps changing. I have been told that a reason to this failure would be the fact that I use a cable to connect LM317 to PCB and I have to shorten it.
What else can be the reason? Please tell me how to fix this.
Thanks in advance.
I'm supposed to build a circuit with a transformer. It's going to take 220V mains as the input and convert it to DC in a magnitude range of 1.25V to 12V. There shouldn't be any ripples in the output signal with an input of 176V to 264V. However my circuit starts to ripple around 230V when the input rms value is decreased from 264V. Also I cannot have steady display of the output signal on an oscilloscope. It vibrates up and down. When I try to measure it with a digital voltmeter it again won't give a distinct result. It keeps changing. I have been told that a reason to this failure would be the fact that I use a cable to connect LM317 to PCB and I have to shorten it.
What else can be the reason? Please tell me how to fix this.
Thanks in advance.