The 10V pulses could drive the gate of a 2n7000 MOSFET, source connected to 0V. The connect the drain to one of the parallel port input pins with a pull-up resistor to +5V, perhaps 4.7k.

Good advice but it sounds scary, I would have loved a circuit that incorporates a optocoupler so that the Hall effect circuit and the pc circuit are isolated from each other.

 

EDITED


Sure, but, as I said, "This is going to depend on what you mean by "the parallel port". PCs stopped using these ports long ago and you need to first see what you have on this old 386."

The original PC parallel port was designed as a printer interface and had an 8-bit port and a 5-bit port and a 4-bit., in fact, it did not have to be bidirectional. It need to have to be and frequently was not. It was there to accommodate the Centronics interface.

A few feet from where I am typing is an old XPmachine that has a PP card that I purchased - fully bidirectional - goes much further than the original LPT interface specification.

Of course there are programs to control the port, hundreds if not thousands of them. So what?

The first step, again, is to see what the TP has on the machine. Maybe the TP already has done that or maybe he just sees a connector on the back or maybe not. That is why it is the first step.

The reason I mentioned the older version of VB is because, as I recall, it has plenty in it for support of PP and, again if I recall, you can actually get it and uses. Can't get much easier than VB for programming.

I don't know what you were suggesting with your response - please explain how it relates - especially to the first step....and don't assume I am "upset", I am simply responding, just like you.

Thanks for showing effort but u did not grasp my post too well. Try and relax when reading the posts, if I did not have a parallel port on the old 386 I would not be trying to send info to it. The post is not asking for software to read the port, it is requesting for a circuit that can safely convert 10v pulses into a something a computer can digest safely.

 

I bet it's got real com ports maybe even 4 of them wonder what they could read with a home made driver.

Using com ports would require a lot of extra hardware, Its a bare bones project.

 

As above, my guess is that nothing more than a 5 V zener will reduce the tach output voltage to a safe level (+5 V). If that makes you nervous, try a resistor to GND. If a 2.2K-4.7K resistor causes a decrease of something like 1 V or more, then it is a safe-er bet that the output is open collector with pullup. If the output doesn't drop much, then you probably can put a 2-resistor divider on it to get the peaks below 5 V. A third option is as above, a 2N7000 small signal MOSFET (with a pullup resistor to +5 V) as an inverting high impedance buffer. If you are examining the tach signal only for frequency, then the inversion doesn't really change anything.

No matter what, you'll have to write either a polling routine or an ISR to capture the signal transitions fast enough to calculate the freq.

Yet another option is a missing-pulse detector circuit, basically a retriggerable monostable. With this circuit you get a logic high/low signal when the tach freq is above/below a trip point value. It is a low pass filter followed by an analog comparator.

NOTE -=- ALL of these ideas are based on the motor ground (power return) and the PC signal ground being tied together. If that is not the case, things change. One possibility is that the tech sensor is a circuit that is independent of the motor power circuits. Example - this is almost always the case in AC powered fans that have a tach output. In this case, the tach output has 3 wires that are independent of the motor power wires. How is your motor configured / specs / part number / photo?

ak

 

I agree. The thread title and post #1 are perfectly clear, and contain all of the information necessary to provide assistance.
/-- wisdom snipped -/
How is your motor configured / specs / part number / photo?

ak

Could not agree more. Clearly, I am not as relaxed as you and it was absolutely necessary to add your agreement without a quote - that is the hallmark of both clarity and civility and there is no way that you could not add that comment. Yet, in the midst of all that wisdom, you are actually asking for more information to provide assistance in the same post that starts out by saying that post #1 had all the information necessary to provide assistance - Maslow had nothing to worry about.

Edited to add: For the record, the post that was partially quoted here has been edited (without stating as much) to remove both the initial and ending sentence. The post was accurately quoted by me.

 

MOD NOTE: Let's keep the tone civil and the snarkiness to a minimum, folks. Everyone just please take a deep breath, take a step back, whatever you need to do. Then please remember that written communication is full of opportunity for miscommunication as everyone brings their unique experiences to the interpretation of what other people write.

 

, "This is going to depend on what you mean by "the parallel port". PCs stopped using these ports long ago and you need to first see what you have on this old 386."

The original Centronics version was soon replaced with bi-directional version, for byte and nibble bi-directional communication.
It can easily be added to modern MoBo's with a small expansion card, if needed.
Done all the time by the DIY CNC crowd.
Max.

 

The original Centronics version was soon replaced with bi-directional version, for byte and nibble bi-directional communication.
It can easily be added to modern MoBo's with a small expansion card, if needed.
Done all the time by the DIY CNC crowd.
Max.

Ya know Max, I have built interfaces using the Centronics port on old Z-80 boxes. But also also other parallel ports. I have even built interfaces to make parallel ports using an 8255 and an 8212 and all those old chips - even decoding the memory and other lines and using LS chips. I have used many parallel ports for many interface projects over the years - including the software in assembly, BASIC, VB, Turbo-C, and others. I don't know everything about parallel port interfacing, but I do know something about it. Many people were doing this many years ago as it was the easiest way for so many to get into "Real World Interfacing" as it was called.

Those experiences and the resulting knowledge led to me feeling that I had something useful to contribute to the thread. I don't post to every thread that comes along. But look at all the contentious banter. Over what - what was the capital offense - that it is a good idea to first understand the parallel port on the computer you want to use?

How should I respond to your comment "The original Centronics version was soon replaced with bi-directional version, for byte and nibble bi-directional communication."? Would you like an, "ok, you're right and I'm wrong" when all I said was that they were not originally bidirectional. Do you want to provide evidence that every single 386 box has 3 bidirectional parallel ports and they all operate exactly the same, including, the one in question?

It is disappointing because so much of the criticisms in this case appears to be contentious just to be contentious. Now, I don't know you or, more accurately, your nickname very well (I definitely do not know you at all). I do remember a while ago you believing that you had bricked parts of your windows OS when it turned out to be your keyboard - a thread that I contributed to because I thought I had something potentially valuable to contribute. In fact, I don't really track nicknames too well and frequently forget who it was that said things that I find to be, frankly, ignorant to the point of being offensive.

Yesterday, for the first time ever that I know about, one of my posts was deleted. No explanation at all. I called someone out on what they had posted and in no way did I violate any of the terms of the user agreement. This is something that I have seen more than a few people complain about and now I see that issue from a different perspective. As I have said previously, the misconception of perceived anonymity produces a variant of "beer muscles".

Look, I can be banned, I can have my posts deleted and there is really not much I can or would try to do about it. I can even sever, or have my agreement with EETECH severed, with little more than an email (I am a contributer and not even a particularly prolific one).

But, what I will not do is shirk in fear from calling someone out when they are so wrong but feel emboldened by the misperception of anonymity combined with a high-school clique mentality. I usually don't do that and certainly not because someone has thousands or millions of posts and is validated more by likes than logic or results. They are the ultimate authority when their first sentence, which is completely unnecessary and provacative, is exactly the opposite of their last, or when their post has no relevant contribution other than an inaccurate criticism of something that was not said....or, indeed, a pile on post immediately after a moderator warning.

As far as I am concerned, you check your rank at that door. If I am wrong, I will say so and if I believe others are wrong, I will also, on occasion, say so as well.

As for this thread, yes, I am going to back out now. I tried to contribute but it is not what the TS and people like you are interested in. That is no problem for me and I have made my points for all to see.

Edited to add: I referred to having a post deleted without explanation. While that was true at the time that I wrote it, I have subsequently received an alert (without the user's name) that says the post was deleted with the reason "Sarcasm uncalled for"

 

Good advice but it sounds scary, I would have loved a circuit that incorporates a optocoupler so that the Hall effect circuit and the pc circuit are isolated from each other.

That should be no problem. The optocoupler would need some current, say 1 - 10ma. So how much current can be drawn from these 10V pulses? Can you connect a resistor 2k to 10k and see what happens to the pulse voltage?

The circuit below will do the job if there enough current available. It's just a case of selecting a value for R1.

 

As above, my guess is that nothing more than a 5 V zener will reduce the tach output voltage to a safe level (+5 V). If that makes you nervous, try a resistor to GND. If a 2.2K-4.7K resistor causes a decrease of something like 1 V or more, then it is a safe-er bet that the output is open collector with pullup. If the output doesn't drop much, then you probably can put a 2-resistor divider on it to get the peaks below 5 V. A third option is as above, a 2N7000 small signal MOSFET (with a pullup resistor to +5 V) as an inverting high impedance buffer. If you are examining the tach signal only for frequency, then the inversion doesn't really change anything.

No matter what, you'll have to write either a polling routine or an ISR to capture the signal transitions fast enough to calculate the freq.

Yet another option is a missing-pulse detector circuit, basically a retriggerable monostable. With this circuit you get a logic high/low signal when the tach freq is above/below a trip point value. It is a low pass filter followed by an analog comparator.

NOTE -=- ALL of these ideas are based on the motor ground (power return) and the PC signal ground being tied together. If that is not the case, things change. One possibility is that the tech sensor is a circuit that is independent of the motor power circuits. Example - this is almost always the case in AC powered fans that have a tach output. In this case, the tach output has 3 wires that are independent of the motor power wires. How is your motor configured / specs / part number / photo?

ak

Thanks for ur idea, the sensor on the motor will have a 15v independent power supply coming from a voltage regulator. As per the current it will draw, I dont know. Current rating always seems to be an unknown in most of my circuits cos practical is different from theory. The sensor is equipped with 4 wires, 2 for the power and the other 2 the 10v pulse signals in relation to ground. If I am to follow ur advice and use a zener, I am not sure what pin on the lpt port will accommodate this because there is already a high of 5v on some of the input pins. The status of the input pins on the lpt at startup is unpredictable. I think its a shame that this aspect of things is confusing me because I have successfully completed the output circuit. I learn that I should put an inverter at the input pin but this does not compute with me as my definition of an inverter will not work here.

 

That should be no problem. The optocoupler would need some current, say 1 - 10ma. So how much current can be drawn from these 10V pulses? Can you connect a resistor 2k to 10k and see what happens to the pulse voltage?

The circuit below will do the job if there enough current available. It's just a case of selecting a value for R1.

I dont know how much current, its always an unknown factor. Thanks for the circuit u presented and it did cross my mind only that I found out that the lpt port will only tolerate a certain type of voltage. Its best to take voltage from a pin on the port and regulate it back into the port.

 

That is a Fischer-Paykel type out-runner motor, isn't the 5 pin connector for the sensors?
I would have thought it would have been +/- and 3 for the sensors being as there is 3 stator windings as per a BLDC motor.
Max.

 

That is a Fischer-Paykel type out-runner motor, isn't the 5 pin connector for the sensors?
I would have thought it would have been +/- and 3 for the sensors being as there is 3 stator windings as per a BLDC motor.
Max.

I have not had the opportunity to measure any of the voltages supplying this stator, Im simply going by info picked up here and there. It is a 4 pin connector and this is a more updated version of the Paykel motor. It has been really difficult to get any spec on this particular engine but Im confident that I will get there in the end.

 

There are a few posts out there via Google on those that have made generators out of them.
Usually the stator windings are H.V. AC.
Max.