900ct 8ohm transformer. what means ct?

[J_Nichols]

I'm building a circuit to work with audio. In the schematic, I read 900CT
**broken link removed**

What means CT?
Do I need to use a 8 ohm speaker?

 

[Nigel Goodwin]

Centre Tap, and yes you need an 8 ohm speaker.

 

[ericgibbs]

I'm building a circuit to work with audio. In the schematic, I read 900CT
**broken link removed**

What means CT?
Do I need to use a 8 ohm speaker?

hi,
CT is short for Centre Tapped transformer [ that wire in the middle of the secondary 900 is the CT]

Yes, you should use a 8R speaker.
E

Nigel: almost.

 

[J_Nichols]

Thank you to all.
And 900? What means?

 

[Nigel Goodwin]

Thank you to all.
And 900? What means?

That's the impedance of the primary (900 ohms input, 8 ohms output).

 

[audioguru]

I think the strong resonance of a speaker causes it to be an awful microphone. At a gas station the cheap intercom is usually like that and it sounds very boomy.
I worked with high quality intercoms that used electret microphones and they sounded perfect.

 

[MrAl]

Hi,

That transformer has an 8 ohm output that would normally be used with a speaker of 8 ohms, but that's if the primary driver impedance is 900 ohms. If the primary driver impedance was 1800 ohms, then the output impedance would be 16 ohms and an 8 ohm speaker would load it down too much. However, because it is marked with 8 ohms and 900 ohms it is probably made to be used with an 8 ohm speaker and 900 ohm driver, and although we could use it with 16 ohms and 1800 ohms it would not be as good an idea to use it with 4 ohms and a 450 ohm driver because if it is specified as 8 ohms output then the internal resistance is probably set such that it does not drop too much voltage with an 8 ohm load, as with a 4 ohm load (and matching driver) it would drop more voltage. Whether or not this hurts the application appreciably depends on the power level and the power handling capability of the transformer, ie a 4 ohm speaker requires less voltage to run at the same power level as an 8 ohm speaker.