Changing square wave

[Rouzbeh]

Hi fellas
How can i change a -24v square wave 100khz to 5v or 24v square wave

 

[SparkyChick]

Need more information... depending on where it originates and how things are connected, it could be as simple as connecting the ground to the +ve input and the signal to the ground, but without knowing the full details of what it is, where it comes from, what it's connecting to and how those two items are interconnected it's almost impossible to say beyond the vary obvious answer of 'a signal converter'.

The only thing that springs to mind for the later is an operational amplifier configured as an inverting amplifier, but again I'd say without knowing all the facts it's very hard to give anything nearing a definitive answer.

 

[marconi]

To help us help you please tell us more or draw an image of the waveforms you have and want to produce.

And tell us too what currents are to be sinked and sourced during the space and mark of the square wave (or mark and space if it is this way around).

See: Current Sinking and Sourcing Explained - https://startingelectronics.org/articles/current-sourcing-sinking/

and 'rectangular waveform' section in

Electrical Waveforms and Electrical Signals - https://www.electronics-tutorials.ws/waveforms/waveforms.html

 

[Rouzbeh]

Thank you for your consideration, this wave is produced by an npn incremental ncoder witch provide a square wave that amplitude range is (-24,0)v and its frequency is 100khz i need to connect it to a high speed counter witch connected to siemens 1500 cpu the problem is this high speed counter does not have the configuration that is compatible with npn ncoders i need to change the amplitude range from (-24,0) to (0,24).

 

[SparkyChick]

Take a look at this:-

https://uk.rs-online.com/web/p/interface-relay-modules/5329980/

Based on 10 minutes of Googling, it appears that this should allow you to do what you want although I'm not sure about the frequency range that device will handle.

 

[Spoon]

Take a look at this:-

https://uk.rs-online.com/web/p/interface-relay-modules/5329980/

Based on 10 minutes of Googling, it appears that this should allow you to do what you want although I'm not sure about the frequency range that device will handle.

Looks like the max frequency of that device is 15kHz

 

[SparkyChick]

The principle is there though... it's highly unlikely this is the first time anyone has had to do this and based on my Googling there are quite a few pages that have information about connecting NPN encoders to PNP inputs.

 

[Wilko]

How about a resistive divider and isolating transformer?

 

[marconi]

Isocom SFH615A-2X Optoisolator 1 Channel 63-125% CTR 5.3KV DIL-4 - https://www.rapidonline.com/isocom-sfh615a-2x-optoisolator-1-channel-63-125-ctr-5-3kv-dil-4-63-1417

https://www.rapidonline.com/pdf/58-0510e.pdf

You could consider using an opto coupler chip. Use the encoder output (0,-24V) to drive the opto-diode emitter (with a suitable current limiting series resistor) and use the opto-detector phototransistor (npn), connected common emitter, to provide (5V,0) or (24V,0) at its collector with reference to the ground/emitter.

See common emitter transistor circuit:

Transistor as a Switch - Using Transistor Switching - https://www.electronics-tutorials.ws/transistor/tran_4.html

You need to know the input impedance of the CPU input and what currents are required to be sourced to the CPU input in the high state(5V or 24V) and to sink the input in the low state (0V) in order to work out the value of the collector load resistor and check that the photo transistor can switch the emitter -collector current without overheating.

The chips I have referenced have a maximum collector-emitter voltage of 70V and a cut-off frequency of 250kHz. The switch on and switch off times are circa 2microseconds.

If the encoder's 24V power supply is galvanically isolated from the CPU's you can use it to provide the power for the photo-transistor switch. So, 0V becomes +24V and -24V becomes 0V. If there is not galvanic isolation or the risk that the galvanic isolation will be bridged you will have to provide a separate dc power supply of (5V,0) or (24V,0).

Best I think to do a test circuit before connecting to the CPU.

 

[Darkwood]

I would suggest a signal conditioner would be the suitable option here, they come in many forms and tolerances giving a wealth of options to suit ones needs.

 

[marconi]

Siemens coupling relays and signal converters:

Coupling Relays and Signal Converters - Industrial Controls - Siemens - http://w3.siemens.com/mcms/industrial-controls/en/control-devices-monitoring/relays/coupling-relays/Pages/default.aspx

 

[marconi]

SIRIUS 3RS70 signal converters:

SIRIUS 3RS70 signal converters - Industry Mall - Siemens WW - https://mall.industry.siemens.com/mall/en/WW/Catalog/Products/10255287

 

[static zap]

Do you have actual details of encoder ,as sometimes apparent
polarity issues ,occur just due to "Maths" and pnp / npn specs !
(and an inherent fear of crossing the streams)