Voltage drop when ferrite core transformer is connected

[ss]

Impedence matching???

Hi
I am gettign a 4 Vpp signal when i connect the frerrite core trasnormer it drops down to 0.1V at the input ( where it was 4Vpp).
Plz tell me how to solve this problem


Bye

 

[willyboy19]

Re: Impedence matching???

You need to be more specific to describe your problem: what is the signal frequency? What is the transformer model you are using in your simulation or actual board?

 

[flatulent]

Re: Impedence matching???

The winding inductance of your transformer should have a reactance at the lowest operating frequency that is 3-5 times the resistive component of the load.

Even if this is true, the current sourcing-sinking capacity of the driving electronics must be able to supply the current drawn by the load impedance presented to it.

Here are some measurements to try.

1. Vary the frequency and see if things get better at higher frequencies. This indicates the inductance problem.

2. Vary the signal level and see if the waveform level becomes related to the drive level at low values. This indicates the current problem.

 

[ss]

Re: Impedence matching???

I am working on the power line communication project.
I have implemented FSK modulation and demodulation using XR2206 and XR2211 respectively.
I am getting 30khz and 15KHz, 5Vpp output for logic 1 and logic 0 respectively.
I have also implemented the coupling circuit using ferrite core from the power supply and couple it
using .47uF - 300V capacitor(capacitor conected on the high voltage side) . Now the problems comes when i integrate the ouput of the FSK
with the input of transformer. After connecting the transformer with the ouput of FSK
the voltage drops from 5Vpp to 0.1Vpp.

Please tell me any idea to solve this problem

Waitng for positive reply.

Sarmad

 

[Borber]

Re: Impedence matching???

What is your transformer windings ratio. Power line is low impedance load and you should have step down transformation to it. If transformation ratio is low you would short circuit your output circuit. It is impedance matching case. What happens if you connect only primary end of transformer, does the voltage stil drops. If so you have inductance problem it is too low.