Re: [EVGRAY] Re: Winding BiTT with C shape winding tool

Body

Hi Gerry,

There is much noise in the current measurement. If measuring across a low resistance current shunt a 50 Ohm BNC feed through at the input of the scope and a 50 Ohm coaxial cable to the shunt resistor will remove much of the noise. As resistors generates a lot of noise the usually 1 MOhm impedance of scope inputs is too much impedance mismatch to a 50 Ohm cable (probe X1) like a short compared to the 1 MOhm input. This causes a lot of reflections along the cable which drowns the signal in noise. The 50 Ohm input absorbs the signal instead of reflecting it. Only the source end of the cable is then mismatched and thus will reflect signals coming from the scope input end where no signal is sent from so no or less noise is generated.

"The slightest error in the phase measurement makes a huge difference to the efficiency results."
And for calculating the power is needed a complete cycle neither more nor less. A rule of thumb is to average the power measurement over 20 cycles. Then the error is minimized if not having a full number of cycles to multiply.

The secondaries aren't wound close to the core. Bill Alek doesn't do that too. This will induce a field of opposite direction through the air part of the coil. This is like a secondary if the coil is used as a primary. It makes big stray fields into the ambient.

The phase shift could be that of a transformer at no load. Then it is acting just like an inductor. I.e. it's having pure reactive power.

Regards
Ole
 

---In [email protected], <smokyatgroups@...> wrote :

 Hi Doug Ole guys, In the BITT circuit I was wondering is most of the losses only occur at low power levels.
 As I have never gotten OU out of it even though Lenz effect seems to go away.
 

 So I made up a simple (although not terrific) version out of some Microwave Oven Transformer (MOT) cores and coils.
 Tested at low signal inputs and also high 240V ac levels from car battery and inverter.
 My best results at 240Vac gave 2.91 Watts out for 2.78 Watts in.
 

 Other more typical & less than OU results are shown on the attached pics.
 The slightest error in the phase measurement makes a huge difference to the efficiency results.
 

 The primary for BIIT input I used was the High Voltage winding.
 The secondaries were two primary coils off MOT
 

 Yahoo doesn't want more than 2 attachments 
 will send 2nd email with other 2
 

 Gerry