single ended signal to differential signal?

Unbalanced to balanced? What is the signal? And just how far are you sending it using which cable?

--
*Nostalgia isn't what is used to be.

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Okay: the signal is a few millivolts around 2V, but it can go up to full 5 Volts in the extreme case. The cable used is a category 5 cable, about, I think, 8 meters in length. I'm just the poor guy having to solder it all together, so I can at this time not make much from the terms balanced or unbalanced. With an average of 2V the signal has a definetive offset, and it needs being DC coupled into the TL072 acting as line driver for the differential line. I find no infos on the net for that kind of setup, and it wonders me, for there are tons of scenarios where the reverse is being done.

Single ended

Differential (audio terminology)

Is it an AC signal riding on a DC level ?

What kind of signal are you dealing with here ?

Graham

One simple answer is to have another 1/2 TL072 wired as a unity gain inverter driven from the original output, driving the other input of the differential amp. Note the 6dB extra gain you get this way.

I'm not entirely clear why this is necessary over only 8 metres of cable run though. Are there interfering signals ?

Graham

There is the basic concept:

The opamp on the right side is just to symbolize the input of the PC-card where the sampling takes place. It's software can control the impedance and other aspects of the cards inputs.

The signal is from a K-Band Transceiver, a small radar. And the noise I get on the lines that run through a room filled with servers is enough to add so much ambient noise that single opamp "boosted signals" contain too much noise than to make use of the values received, for then stronger signals would produce clipping.

I understand.

What is the bandwidth of the signal ? Is it purely an AC signal or do you *need* DC coupling ?

Graham

Then you ask where it belongs, in sci.electronics.basics

THis isn't about basics, this isn't about design, this newsgroup is about the repair of electronic equipment.

Read Mark Zenier's guide to the hierarchy before you mispost again: ftp://ftp.eskimo.com/u/m/mzenier/seguide9706.txt

MIchael

Okay - the last word after a lot of datasheet reading is now a MAX435 - it's a wideband Transconductance Amplifier. I just need to find out how to give it a variable gain without ruining the impedance of it's output, and then I am fine.

Thank you all very much for the help you provided to me!

There would be many chips you could use. You can even use a TLO72, but usually one with a more heafy output drive is used. What is the terminating Z ? What is the response needed?

greg

This is not ideally suited to this task.

Graham

Michael.... Not so fast here ! .... let us not get so specialized and so quickly send people off to other newsgroups. There are plenty of folks on this "repair" newsgroup that are not only qualified to answer these types of "design" questions but also are very happy to contribute. Most repair techs have always had some design and installation experience and can many times propose a simple, practical and workable solution that some design people sometimes ignore in favor of a more complicated, engineering eloquent and troublesome solution. Daniel Sofie Electronics Supply & Repair

- - - - - - - - - -

You still haven't said what the signal is. Audio? Video? SHF? ;-)

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*I used to have an open mind but my brains kept falling out *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Take a look at the Analog Devices SSM2142 Balanced Line Driver

for the single-ended to balanced line (differential) function. AD also has a mating differential line receiver, the SSM2141 High Common-Mode Rejection Differential Line Receiver at These units are quite good at handling high common-mode signals (induced noise).

Since you haven't mentioned the exact nature of your signal, such as frequency range, required gain and gain accuracy, etc, I'm assuming that it's in the audio range, and gain accuracy is a secondary consideration. These two units are designed specifically for professional quality audio equipment, and will easily fit that requirement. If your signal requirements are different, such as video, digital, etc, then you need to come back to us for a more meaningful answer. We can't give precise answers to ambiguous questions.

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Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the 
address)

Life is like a roll of toilet paper; the closer to the end, the faster it goes.

I dont think youre giving the required information, its all very unclear, both here and in your follow up.

So I'll just mention a general principle: interference can be more or less wiped out by reducing line driver impedance. With low impedance drive, runs far longer than 8m are possible with single ended signals.

Opamps do not give as low z output as would be ideal. If your signal is in the af band, an audio amplifier may be a simple low cost way to get R_out in the region of an ohm or less.

NT

It's a radar - The frequency varies with the speed of items approaching or moving away, the distance they are away, and such stuff - its a tiny doppler-radar. I have - honestly no clue, for there is no information upon the maximum frequency-shift in this manual, nor does my boss know what things he actually wants to focus on.

It is a InnoSent IVS24-2-4-2-162 K-Band VCO Trasceiver

The MAX will do it's job pretty well - DC coupled and capable to transmit up to 200MHz - more our digitizer-card cannot handle anyway.