Question: Digital 0-10V signal to 0-110V signal

[Kova]

Hi all guys,

I have a "serious" problem with 2 interfaces..I explain better .
I have an interface with 4 digital outputs that works with 0-10VDC level and I have another interface with 4 digital inputs that works with 0-110VDC level.
My question is simple: is there some way to 11x amplify the output digital signals to adapt to the other inputs?

I tried to search some DC-DC boost converter  (single power supply at 24VDC, it would be great) but without any luck

Some idea/help?
Thank you very much in advance for any response.

Bye :-)

[Gallymimu]

Is this for an industrial control application?  is the 0-110V meant to work with AC or DC voltage (I'd guess AC).  It makes a big difference.

The easiest way to do this is with some relays.

[thunderer]

I would see it like this (the OP says is Vdc for both). A simple voltage amplifier by using a transistor repeater. Remember you will have a reversed variation, but you can solve it in the PLC (?) you use.

1. If the 0-10Vdc is not PWM, I'd make it PWM.
2. You attack the base of a transistor repeater with this PWM. The repeater has to have Vce bigger than 110Vdc, as the supply will be minimum 111Vdc.
3. You filter the new 111Vdc to smoothen the signal.

OR, you use the Texas chip but with limitation to 100V. See link http://www.ti.com/product/opa454.

OR see this 200V power amp http://www.ti.com/product/lme49811. But I do not know if this is OK for your impedances.

[Gallymimu]

oh yeah, VDC gotta read more carefully.  Not sure why you'd use PWM for digital signals, I must be missing something.  I still think relays are the easiest (and safest as they provide isolation) using transistors amps with more than 40-60VDC without isolation, or single fault protection wouldn't pass most regulatory agencies (UL or CE).  If you don't care about safety and isolation you can of course use a simple NPN or PNP/NPN level shifter.

It sounds like one of the issues is generation of the 110VDC supply voltage?  The easiest for that would probably be (to meet regulatory issues) a small isolation transformer off of 110AC or 220AC rectified and filtered.

[thunderer]

Sorry, I misread the digital input/output request (I was thinking all the time analog - thus the PWM, mislead by the 0-10Vdc range). Surelly, a relay is the best choice, maybe an optocoupler too for smaller footprint.

[Gallymimu]

That's okay, I missed DC you missed digital analog.

A lot of help we are huh?!

[solutions]

Again, NOT ENOUGH INFO.

What are the outputs driving?

What are the inputs from and what impedance does it have?

When you say "digital", what levels for high and low, voltagewise.

To get anything useful, you need to fully constrain the problem. You haven't, so it becomes a guessing game.

Here's my GUESS:

From the sounds of it, logic levels in at 0-10V Low-High in, 0V-110V Low-High output, since you are looking for 11X gain.

You don't need a linear 11x amp, in fact it will be a POWER HOG and might get you in trouble by acting as an oscillator ("if you want an oscillator, design an amplifier, if you want an amplifier, design an oscillator"). A simple common source MOSFET will do your logic voltage level translation, though it will be logic inverting. That' easily fixed with two stages of inverters 0-10V 0-10V 0-110V. Again, impedance will determine what you do for the common source load, whether it's a simple pullup resistor, or a P-device, for instance.

More info will get you a finessed answer. No more info will get you the crap solutions you see so far, mine included, because they are GUESSES at what you are trying to do and to what.

[Kova]

Again, NOT ENOUGH INFO.

Hi, thank you for all responses :-)
Yes, you are right, not enough info.

What are the outputs driving?

The output signals come out from a sort (more or less) of PLC with 100mA of OUT currents

What are the inputs from and what impedance does it have?

The high impedance inputs are of another old PLCs, powered at 24VDC but with inputs at 110V (at the input there are FETs and after a step down stage converter used to low the 110 voltage)

When you say "digital", what levels for high and low, voltagewise.

OK, for the first one 0V means 0 (low), 10VDC means 1 (high). For the second one 0V means 0 (low), 110VDC means 1 (high).

To get anything useful, you need to fully constrain the problem. You haven't, so it becomes a guessing game.

I have only a BIG constrain: I can't use a 110VDC power supply, at least a 24VDC!
I already know that the relay solution is the best way to solve the problem, but I can't

Thank you very much again
Bye

[solutions]

You have no choice but to use either the 110VDC in the box you are driving (if there is a pullup on those inputs, you can run the mosfets as open drain output), or to have one in your adapter box. There is no magic in an amplifier 11x amplification with a 24VDC supply gets you 24VDC. A relay won't do anything either if there's no pullup on the inputs.

The MOSFETS will work - better and more reliably than a relay, and they will switch much faster and not fail as quickly. Most power MOSFETS are 20VDC in.

So, you still need to know what the input looks like unless you want to guess.

[Gallymimu]

Without a boost converter you are going to have to come up with a 110V supply voltage.  Unless you can find an off the shelf 24-110V boost converter (I'm not aware of anything like that)

I guess one other very non-elegant cheap way to do it would be to use a 12V input and a power inverter and then rectify / regulate that but it would be a mess for something in an industrial setting.

[Kova]

Thank you again guys for the help!

Yes I think that I don't have enough choices :-(.
All your ideas work well, but I want to propose a new one and I'd like to ask you what you think about.
I want to build a sort of circuit similar to that one used on the mosquito rackets.
For better understand what I'm talking about, this is an example:

http://circuitsdiy.com/miniature-electric-fence-circuit-used-in-mosquito-racket

It works with a flyback topology transformer and it starts from a low voltage (in general from 3V to 12V) and it is possible to reach 1000V (low current obviously).

What do you think? :-)
It's an insane idea ?
It will never work, right ?

Bye :-)

[Gallymimu]

Thank you again guys for the help!

Yes I think that I don't have enough choices :-(.
All your ideas work well, but I want to propose a new one and I'd like to ask you what you think about.
I want to build a sort of circuit similar to that one used on the mosquito rackets.
For better understand what I'm talking about, this is an example:

http://circuitsdiy.com/miniature-electric-fence-circuit-used-in-mosquito-racket

It works with a flyback topology transformer and it starts from a low voltage (in general from 3V to 12V) and it is possible to reach 1000V (low current obviously).

What do you think? :-)
It's an insane idea ?
It will never work, right ?

Bye :-)

That idea occurred to me (and probably to the other guys as well).  Low current voltage multiplier circuits or the flyback as you are stating is basically the boost converter we were mentioning before.  One big problem is the probably going to be the very low current output wouldn't be sufficient to drive anything in an industrial environment unless the inputs you are driving you KNOW to have high enough impedance for what you are doing.  Also keep in mind that the little flyback circuit is likely not producing a very accurate output (as it is irrelevant to the purpose of burning bugs). 

Sure it would work, but designing a RELIABLE, and SAFE boost converter is totally impractical unless it's something you are taking on as a hobby or learning investment.  Power electronics design isn't hard, but it isn't trivial either.

[Ichan]

The high impedance inputs are of another old PLCs, powered at 24VDC but with inputs at 110V (at the input there are FETs and after a step down stage converter used to low the 110 voltage)

Strange device.. Doesn't it easier to modify this input?

-ichan

[thunderer]

A simple question: is a 24Vdc level considered "0" or "1" in the 0-110Vdc range? Or something in between?

PS: The mosquito zapper is overkill, keep it for summer evenings on your backyard deck.

PPS: What PLC type is the 24-110 converter input? Just out of curiosity.

[jumulab]

Hi Kova,
Have you take a look for APEX power op. amps ?.
You have several models of cased TO-03  amplifiers enabled to work until
350 V ( delivering only 75mA). There are model working until 900Vdc.
Only take a  trafo with and ac output enougth higth , rectify them , an
supply the op amp. Only a simple inverting or non inverting configuration and
the mentioned gain of 11 is all you need.
Regards.

[solutions]

^ He STILL needs a 110V or higher power supply - there's no free lunch by using a linear amp or an APEX - in fact, it will probably dissipate a lot of power if the input is slew rate limited.

[DreamCat]

"I have another interface with 4 digital inputs that works with 0-110VDC level."
is this means that this interface has a 110VDC power supply?
if it is, you just need a level shift, such as to use high voltage BJT to build a circuit.
you said "interface", I think it just need very small current to drive.
but In order to protect the output terminal, we must consider to use optocoupler to provide isolation voltage of the two large differences.

but if there is no suppy in 110VDC interface side. you have to build a isolated boost-up converter.

[jumulab]

Hi, I'm sorry for my last suggestion. He supposed that you needed convert the 0-10 V to an analog input range of 0 to 110V.
If you really can not use 110 volts, you may consider modify  the inputs at the system from actual 110 volts in order they can work  in range 0-10V.
If you are able to change/modify the input circuit, perhaps the problem have an easy solution.

Regards

[f22kma]

Sorry if I've missed something, but what is the power requirement at 110VDC?

If not too high, could use dual Mosfets driving center tapped transformer from 24VDC supply with Class-B driver chip (or descrete shoot-through prevention circuit). Output could then be fed-back (for closed loop control if required), rectified and filtered. I think logic control of resultant 110VDC has already been well covered.

If tight voltage regulation under varying load required, then feeback and error voltage to PWM drive (hardware or software) straightforward to implement.

Low cost option is reversed +/- mains step-down transformer with suitable turns ratio. Better performance would be compact high frequency core (but possibly more noisy if not designed well).

Regards.