Floating Pin on Transformer Unused Center Tap

[edmundsj]

Hello,

So I am using transformer to step-up voltage in a very simple circuit. It's a met-23 22.4:1 step-down transformer and I have attached the datasheet below. However, I have no use for the center tap on the primary coil and I'm not sure where to put it. This part will be soldered onto a PCB soon, and I was wondering if I should clip the pin and leave it floating, ground it, or apply a certain voltage across it? I am using a 9V battery as the power source to step up the pulse voltages to around 250V+ when no load is attached. I'm somewhat uncertain what the function of the center tap is, and I don't know if grounding it or applying some other constant voltage would affect its performance. I have tested it with the center tap floating, and it worked as I wanted it to. Thank you.

 

[davenn]

I have deleted your pdf file, it really screwed up my browser and I'm not risking trying to open it again
or risk other people also having problems

give a link to the datasheet
but if it's a normal centre-tapped secondary, just leave it disconnected ... don't ground or anything

Dave

 

[edmundsj]

OK, here is the link to the datasheet, it's possible it was saved as xhtml or something weird. Here is the link: http://www.tamuracorp.com/clientuploads/pdfs/engineeringdocs/MET-23.pdf. Also, apologies, the primary is the one that has a center tap. Not sure if this changes anything.

 

[davenn]

WOWOWOW DO NOT PUT POWER ONTO IT !!!!

That's an audio transformer NOT a power transformer

 

[davenn]

Lets start at the start and describe your whole project
ALL the details any circuits you are working from etc

Dave

 

[edmundsj]

Okay, here are the project details: I'm build a Functional Electrical Stimulation (FES) System to be used on healthy individuals studying the effect of distributing electrical stimulation on muscle fatigue. The design I currently have uses a MOSFET to switch a 9V battery through the transformer below, and steps up the voltage to about 250V+ without a load attached, and with a load that resembles human leg tissue (A 500K resistor in parallel with a 133pF capacitor). With the load attached, the voltage measured on the primary coil maxes out at about 150V or 70V depending on the mood of my circuit. The waveform sent through the transformer is an 80 microsecond pulse at a rate of anywhere from 5-30Hz. Hope that clears some stuff up. The reason I used an audio transformer is that my device was reverse-engineered from a commercial FES device, where they also used an audio transformer of similar characteristics. Hope this clears stuff up.

 

[davenn]

sorry, this is highly dangerous and threads like this are always locked for everyone's
health and legal safety
I suggest you find a mentor that can work beside you ( not via the net) and check everything you are doing

regards
Dave