savvej
Member
I opened up a power adapter to see whats inside.I have attached the pics of it.I tried to reverse engineer and draw the schematic of the circuit.I could'nt relate it with any of convertors learnt at the university.
Now the circuit involves a small transformer.I basically want to simulate the circuit in pspice to study its working.
I wished to know how to find the turns ratio of an unknown transformer.
The power adapter was rated for 10.5V DC 550mA.
Also when I measured AC voltage at the output of the transformer,it was around 10V(ac).
I desoldered the tx.I have a 500ma 230V -11V tx .I tried connecting this tx o/p to the power tx and find the output.From the ratio of the voltages I can find the turns ratio.But as soon as I connected the TX,it(230-11V) became hot and when I measured the voltage across input ,it was almost zero(As if equivalent to shorting).So I added a resistor in series of 33Ohm(1W) and then again the voltage across the primary was zero.Now I know that the resistance in series should be small as compared to the impedance of the transformer.I tried to measure the dc resistance of the tx using multimeter ,it was around 0.6 Ohms.I have no clue regarding its inductance hence I don't know what resistance to put in series to as to get considerable drop across the primary.
Any other idea to find the turns ratio?
One idea which I have is to measure inductance of the coils on both sides(using some inductance meter which I don't have) and considering ideal tx,turns ratio is proportional to sqrt of ratio of inductances of the coils.Actually to simulate the circuit too I require to enter the values of the inductances of the coils rather than the turns ratio.Any thoughts on easy circuits to measure inductance?
Now the circuit involves a small transformer.I basically want to simulate the circuit in pspice to study its working.
I wished to know how to find the turns ratio of an unknown transformer.
The power adapter was rated for 10.5V DC 550mA.
Also when I measured AC voltage at the output of the transformer,it was around 10V(ac).
I desoldered the tx.I have a 500ma 230V -11V tx .I tried connecting this tx o/p to the power tx and find the output.From the ratio of the voltages I can find the turns ratio.But as soon as I connected the TX,it(230-11V) became hot and when I measured the voltage across input ,it was almost zero(As if equivalent to shorting).So I added a resistor in series of 33Ohm(1W) and then again the voltage across the primary was zero.Now I know that the resistance in series should be small as compared to the impedance of the transformer.I tried to measure the dc resistance of the tx using multimeter ,it was around 0.6 Ohms.I have no clue regarding its inductance hence I don't know what resistance to put in series to as to get considerable drop across the primary.
Any other idea to find the turns ratio?
One idea which I have is to measure inductance of the coils on both sides(using some inductance meter which I don't have) and considering ideal tx,turns ratio is proportional to sqrt of ratio of inductances of the coils.Actually to simulate the circuit too I require to enter the values of the inductances of the coils rather than the turns ratio.Any thoughts on easy circuits to measure inductance?