Hello all, I will start off by saying that I don't know <snip> when it comes to circuit design or anything of that sorts, I am familiar with stuff like resistors, transistors, pots, and components like that, but I do not know about complex circuit design. I turn wrenches for a living and would like to build a device that plugs into the helicopter that has a port to read the frequency of 2 sensors on rotating components. This would be a 200-400 Hz signal at 24-30V and convert those numbers to 4 displays. Two to display the direct reading in Hz and the other to to display these values in RPM, alternatively I could have 2 displays and use a switch to change their inputs. There are two inputs, one is multiplied by 2.5 to convert to RPM, the other is divided by 1.4. These are used to adjust rotor and engine RPM so quality of components and accuracy is of importance.

Currently I use a multimeter to read Hz and just convert it manually, but I think it would be fun and interesting to dip my toes in electrical design and learn something new. I have done a bit of reading and it would seem that using a microcontroller would be my best bet. Though I don't know what to really use or how to begin this adventure. Any advice for components or premade circuts to use would be of help as well as any recommended reading for this topic.
Currently this looks like a mile high cliff to climb so anything would help really.

Moderator edit: vulgar text deleted.
A warning to the member: Watch your language. Foul language will not be tolerated.

 

----> https://www.aliexpress.us/item/3256803165806547.html?pdp_npi=2@dis!USD!$6.66!$4.00!!!!!@2103011616884060107136084e1e88!12000025358524295!btf&_t=pvid:4e14edb0-5743-4e7f-9eb7-dd06e3a3462b&afTraceInfo=1005003352121299__pc__pcBridgePPC__xxxxxx__1688406011&spm=a2g0o.ppclist.product.mainProduct&gatewayAdapt=glo2usa

Seems a single display with selector for rpm or Hz. Did not read all the specs. Make sure you are allowed to connect something to the helicopter circuits.

 

----> https://www.aliexpress.us/item/3256803165806547.html?pdp_npi=2@dis!USD!$6.66!$4.00!!!!!@2103011616884060107136084e1e88!12000025358524295!btf&_t=pvid:4e14edb0-5743-4e7f-9eb7-dd06e3a3462b&afTraceInfo=1005003352121299__pc__pcBridgePPC__xxxxxx__1688406011&spm=a2g0o.ppclist.product.mainProduct&gatewayAdapt=glo2usa

Seems a single display with selector for rpm or Hz. Did not read all the specs. Make sure you are allowed to connect something to the helicopter circuits.

Thanks for the reply, it seems that this unit just displays whatever frequency is inputted into it, I need to convert the frequency with some basic math into an actual RPM.

 

Here is a link to a tachometer that uses a PIC16f628A with a 4 digit LED muptiplexed display. It contains the source code so you can modify it to display the speed or frequency. There is also a description of how the software works that should help you.

Les.

 

Thanks for the reply, it seems that this unit just displays whatever frequency is inputted into it, I need to convert the frequency with some basic math into an actual RPM.

By pressing a button, the display reads RPM. Read !

 

Thanks for the reply, it seems that this unit just displays whatever frequency is inputted into it, I need to convert the frequency with some basic math into an actual RPM.

There is a company that sells exactly that item, that counts frequency and then displays what could be RPM or gallons per minute, if it is from a flow meter with a frequency counter. The company is RED LION. They have a huge product line, and helpful applications people.
BUT you will need to avoid profanity when talking to them. Also when communicating with me. I am a bit picky about that.

 

By pressing a button, the display reads RPM. Read !

Good advice. If YOU had followed it, you'd have seen that the input signals aren't once/rev.

 

The "Red Lion" counter I used would display the scaled units only, until it was reprogrammed. so once set, that was it. Not a cheap device, but able to perform flawlessly.
The added benefits were that it was mechanically durable, and easy to duplicate. If another one was needed it was simple to order and program. No need to assemble another converter and adjust it.