Hi forum!
I have a circuit to reverse. The circuit receives audio input through a transformer (shell core transformer-- and as i guess from a 600 ohm line/device). Similarly the circuit outputs to a 600 ohm line/device through the same transformer. Please see the attached for having an idea.
You can see the labels -3.5dBr/600 ohm and -3.9dBr/600 ohm at the input and otput sides. On the input side, there is a 1.2K resistor in parallel with a series combination of two 470ohm R's and the transformer primary. The secondary is conencted to 130 ohm R. Similarly at the output there is similar topology except for slight change in resistor values.
The transformer turn ratio is nearly 1. Does this fact and the 600 ohm lables indicate that the device driving the input transformer and the device driven by the output transformer are 600 ohm devices/lines? What exactly is the purpsoe of these transformers here?
Does the resistor network surrounding the transformer is some standard topology to interface to 600 ohm lines/devices?
I cant get the exact transfomer part #. Its obsolete. What commercial type 600:600 ohm transforemr can anyone recommend?
Your help if highly appreciated.
I have a circuit to reverse. The circuit receives audio input through a transformer (shell core transformer-- and as i guess from a 600 ohm line/device). Similarly the circuit outputs to a 600 ohm line/device through the same transformer. Please see the attached for having an idea.
You can see the labels -3.5dBr/600 ohm and -3.9dBr/600 ohm at the input and otput sides. On the input side, there is a 1.2K resistor in parallel with a series combination of two 470ohm R's and the transformer primary. The secondary is conencted to 130 ohm R. Similarly at the output there is similar topology except for slight change in resistor values.
The transformer turn ratio is nearly 1. Does this fact and the 600 ohm lables indicate that the device driving the input transformer and the device driven by the output transformer are 600 ohm devices/lines? What exactly is the purpsoe of these transformers here?
Does the resistor network surrounding the transformer is some standard topology to interface to 600 ohm lines/devices?
I cant get the exact transfomer part #. Its obsolete. What commercial type 600:600 ohm transforemr can anyone recommend?
Your help if highly appreciated.
Attachments
This looks like a telecom application.
RS and Farnell, still do 600 ohm transformers. Whether they are wholly suitable, we'll have to wait for a telecome person's opinion 😉
RS and Farnell, still do 600 ohm transformers. Whether they are wholly suitable, we'll have to wait for a telecome person's opinion 😉
dhaen said:
Hi,
I haven't telecom background, but I can say that this circuit looks like old audio telephone hybrid. Almost any 1:1 audio line transformer with static isolation between primary and secondary windings will be good.
Regards
Milan
It does not look like a hybrid to me. It looks more like a unidirectional regenerator for 4-wire circuits.
But like said before, you need a 1:1 telephone transformer. I do not know how much space you have, or what transformer was in it, or what application it is, so I can only give some general dirctions.
The transformers are there for electrical isolation and balancing.
The resistors do have a function in setting the input/output impedance and levels, so if you change to a widely different transformer, you will need to change them.
Go take a look at companies like:
Etal: http://www.profec.com/products.htm their datasheets give info on how to connect the transformers
Umec: www.umeu.de (and look for telecom>fax/modem transformers)
Datatronic: http://www.datatronics.com/
But like said before, you need a 1:1 telephone transformer. I do not know how much space you have, or what transformer was in it, or what application it is, so I can only give some general dirctions.
The transformers are there for electrical isolation and balancing.
The resistors do have a function in setting the input/output impedance and levels, so if you change to a widely different transformer, you will need to change them.
Go take a look at companies like:
Etal: http://www.profec.com/products.htm their datasheets give info on how to connect the transformers
Umec: www.umeu.de (and look for telecom>fax/modem transformers)
Datatronic: http://www.datatronics.com/
Salute to Islamabad!
from: www.73.com/a/0128.shtml
Mouser p/n: 42TL016.
Audio coupling transformer, 600/600 impedance, center tapped. Primary DC resistance: 65 ohms, secondary DC resistance: 55 ohms.
Size: .46"H x .59"W x .55"L
Priced below market.
$0.89 Ea/100, $0.80 Ea/500, $0.70 Ea/1000, $0.60 Ea/5000.
from: www.73.com/a/0128.shtml
Mouser p/n: 42TL016.
Audio coupling transformer, 600/600 impedance, center tapped. Primary DC resistance: 65 ohms, secondary DC resistance: 55 ohms.
Size: .46"H x .59"W x .55"L
Priced below market.
$0.89 Ea/100, $0.80 Ea/500, $0.70 Ea/1000, $0.60 Ea/5000.
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