How to scope transformer secondary

Hello,
i am trying to display the waveform on the secondary of a (low voltage) transformer secondary. It´s a self-built 1:1 transformer at 12 volt.
I can see the signal on the primary as my scope ground alligator clip is connected to common ground.
But on the secondary side, there is no common ground so i connected the alligator clip to one side of the load which for test purposes was a 15 Watt lamp and the other scope probe hook onto the other side of the lamp.

Is that the right way to scope the secondary?
Because except some tiny millivolt spikes i did not get any signal.

I am new to measuring and transformer building and want to learn more about it, so my question might cause some frowns but i hope someone more knowledegable with
these issues might be able to help.
Thanks.

xeno said:

Hello,
i am trying to display the waveform on the secondary of a (low voltage) transformer secondary. It´s a self-built 1:1 transformer at 12 volt.

Click to expand...

I assume that there is 12v into the transformer and 12v out of the transformer.

xeno said:

I can see the signal on the primary as my scope ground alligator clip is connected to common ground.

Click to expand...

What is "common ground" ?

xeno said:

But on the secondary side, there is no common ground so i connected the alligator clip to one side of the load which for test purposes was a 15 Watt lamp and the other scope probe hook onto the other side of the lamp.

Is that the right way to scope the secondary?
Because except some tiny millivolt spikes i did not get any signal.

Click to expand...

It sounds as though you have connected correctly.
Was the 15w lamp illuminated?
If it was, there was obviously voltage there and your scope leads were not making good contact.

JimB

Thanks for the reply JimB. It also turned out that i have a really bad coupling between primary and secondary and have to catch up with learning how to design the transformer properly.

Aren't they expected to be isolated from each other? Do primary and secondary in your trafo have any point in common?