Diode Testing on Breadboard

[rossbalch]

Hey folks, I've been doing some testing with diodes using my breadboard, except I've run into an issue, no matter how I hook up the diodes, I'm always getting asymmetric clipping. It doesn't matter whether they are silicon, germanium etc.

This is as measured with my oscilloscope using a 2.4v peak to peak 1000hz sine. I'm pretty sure my bread board layout is equivalent to a regular hard clipping arrangement like this. R1 is a 1k resistor, though same result without the resistor.

I feel like I must be missing something here? Shown below on the oscope is a pair of 1n4148

 

[GAStan]

Do you have the probe ground on signal ground?

On your sig gen is there a voltage offset? Put your o'scope on DC coupling and look at the input signal, it should be 50% above 0 volts and 50% below.

Also try moving the resistor from the input to between the diodes and ground. It should be diodes>resistor>ground. Put the sine input to the ungrounded side of the diodes and the probe to the junction of the diodes and resistor. The idea is to put the signal through the diodes.

 

[rossbalch]

You're right definitely looks like DC offset. What I can't figure out is why? The signal generator has no settings for dc offset, why would you set up a sine wave this way by default?


For comparison a sine wave sent out of my interface via a tone generator plugin.

 

[GAStan]

Try adding a capacitor in series with the signal in from your sig gen to block the DC offset using your original setup.