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# How to design a speed sensor circuit with a monitor

## How to design a speed sensor circuit with a monitor

(OP)
Hello guys,

I want to design a speed sensor which can sense the speed of a roller coaster and put the circuit on the track. Then, the circuit can transmit signals to a monitor that is about 100m away form the sensor to show the speed of the roller coaster.

Is there anyone know how to design it?

I want to use a hall effect device to sense the speed but I don't know how it can show the speed on a monitor.

I am still doing a lot of research on it. If anyone has similar experience or useful information. Please that me know.

Thank you very much!

### RE: How to design a speed sensor circuit with a monitor

As usual, the Arduino comes to the rescue!

A magnet or a piece of steel, an inductive pick-up (proximity sensor) or a reed relay (if you use a magnet), reciprocal speed measurement. There you are - a speed sensing circuit which can resolve down to better than one percent. Time out when speed is low and show <10 km/h (or some other message).

There are numerous "shields" that can be used. Including radio transmitters. Just add one and you have the information stationary on ground. The rest is also trivial. Use a TV screen or a display or whatever.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

### RE: How to design a speed sensor circuit with a monitor

Sounds like homework. Just how much research have you done? A hall sensor will give a pulse of a certain duration. Multiply that number by something and you will get speed. Can all be done with a UNO. If going 100M, you might want to PWM speed to get DC voltage and send that to DC panel meter to read speed.

### RE: How to design a speed sensor circuit with a monitor

Reciprocal speed measurement does it. Used all the time on paper machines and steel mills. Just do it.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

### RE: How to design a speed sensor circuit with a monitor

I'd not bother with a Hall Effect sensor. You have to get too close to the track or passing cars.

Just use a retro-reflective or transmitter/receiver pair of optical sensors. Time the period between cars (since they're a fixed length). Speed = distance/time. Count the time from when the sensor starts to see something (the car) to the time when it can no longer see it. Use that time in the above equation. Generate a speed for every car and leave the last speed up on the display.

Examples of photoelectric sensors

Keith Cress
kcress - http://www.flaminsystems.com

### RE: How to design a speed sensor circuit with a monitor

??? Explain.

You get new speed information every time the wheel turns. Do you really need better?

Believe me, I use this technique to measure speeds on winders during acceleration, winding and deceleration. No probs.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

### RE: How to design a speed sensor circuit with a monitor

Doesn't peter want to read the speed of the car continuously? And transmit the result to a receiver on ground?

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

### RE: How to design a speed sensor circuit with a monitor

"You get new speed information every time the wheel turns. Do you really need better?"

Yes, if it's shaft mounted, but roller coaster cars are generally unpowered, so installing a sensor on the car was probably a non-starter. Therefore, the sensor needed to be close to the track, and therefore needed two detections to determine speed.

TTFN
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Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers

### RE: How to design a speed sensor circuit with a monitor

OK. I see.
But wireless transducers and energy harvesting is being used more and more. So, I don't exclude a car mounted sensor. Batteries are also an option.

Peter? What are you trying to do? Actually.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

### RE: How to design a speed sensor circuit with a monitor

#### Quote:

I want to design a speed sensor which can sense the speed of a roller coaster and put the circuit on the track.
I took this to mean a stationary device.
I may be wrong.

Bill
--------------------
"Why not the best?"
Jimmy Carter

### RE: How to design a speed sensor circuit with a monitor

You may also be right!

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

### RE: How to design a speed sensor circuit with a monitor

(OP)
hello guys,

Thank you for all your ideas.

What I really want to do is: "I want to measure speed of cars". haha.

or put hall effect sensor into wheels and measure frequency or RPM and transmit data remotely to me.

### RE: How to design a speed sensor circuit with a monitor

OK. Then use my method.

But why Hall sensors? A simple reed switch and a magnet is better in every respect. Less distant dependent, less power consumption (zero) and better temperature stability.

Use a simple low pass filter (around 1 ms) and a schmitt trigger (most micros have that) to debounce the signal. Arduino is perfect for this task.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

### RE: How to design a speed sensor circuit with a monitor

There are commercially available prepackaged instruments to do what you want. Here is one example. Look though the manual.

http://www.instrumart.com/products/40067/red-lion-....

You can use any sensor like a switch, magnetic proximity sensor, or photo cell. It also has programmable alarm functions.

### RE: How to design a speed sensor circuit with a monitor

Is this still a "roller coaster car" or has it changed to "automotive cars" now..

### RE: How to design a speed sensor circuit with a monitor

(OP)
It's still a roller coaster car.

to Skogsgurra: Yes, I'd like to try your way but can you give me more information about Arduino? They have many different product. which one is best for my application?

Thanks a lot!

### RE: How to design a speed sensor circuit with a monitor

Exactly what kind of electrical engineer are you? I see prior questions about how to choose the proper value and voltage for a capacitor, such as 60V caps on a 60VAC system... that's Circuits 101 stuff.

Dan - Owner
http://www.Hi-TecDesigns.com

### RE: How to design a speed sensor circuit with a monitor

(OP)
To MacGyverS2000:

I am trying my best to finish my job. I know these might be a simple question for you but I am lack of experience and have no other partner can discuss with.

I know how to choose a proper capacitor if the source is very stable. However, my situation is different. The frequency is changing all the time and I never meet this situation before so I want to ask about it. I need to deal with many different problems at a time so I think sometimes asking people is a good way to get start. I am not a guy who just ask for answer. I am also doing research to try to get my project done.

### RE: How to design a speed sensor circuit with a monitor

I think that the kind of engineer Peter is - or is not is of secondary imporance. This thread has brought up several ideas and quite a lot of contributions. Peter may not be a seasoned engineer, and his ideas about how to select a capacitor seem less mature. But still, he is on his way. And we shall not discourage him.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

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