Go Back   DIY Go Kart Forum > Building Plans And Advice > Electric Projects

Notices

Reply
 
Thread Tools Display Modes
  #1  
Old 07-09-2019, 09:20 AM
Functional Artist's Avatar
Functional Artist Functional Artist is online now
Senior Member
 
Join Date: Jul 2016
Location: Toledo, Ohio
Posts: 1,772
Thanks: 678
Thanked 684 Times in 535 Posts
Default Digital RPM Meter

Over the winter I ordered a

Tachometer RPM Speed Meter 4 Digital Blue LED + Hall Proximity Switch Sensor (~$10.00)

https://www.ebay.com/itm/New-Tachome...orig_cvip=true

Specification:
Power requirement: DC 8-15V
Measure range:5-9999RPM
Clear zero:Automatic
Clear zero time:about 10s. the greater the RPM value,the longer the clear zero time
Refresh frequency: 0.2-0.5S(120-1200RPM);0.25-0.06S(2400-9999RPM)
Measure indication:RPM<5000,2;RPM>5000,3
Display:Blue 0.56" LED
Sign: Pusle signal,NPN 3 wires normally open
Response frequency:100HZ
Tachometer dimension:72x36x20mm,panel cutout Dimension:68x33mm
Hall proximity model:NJK-5002C
Sensor dimention: M12x10x37mm
Detection range: 1mm-10mm
Proximity output current: 200mA
Detected objects: Magnet
Sensor wiring:brown-Power+;blue-Power-;black-signal
Operating temperature: 0 to 50C.

...to get some "real" data, on the "actual" RPM's, that some of these small electric motors, that we have been working with, are producing

...unloaded & also loaded
Attached Thumbnails
1259234782.jpg   13160755433.jpg  

295141825.jpg  
__________________
RESISTANCE IS FUTILE
Reply With Quote
The Following 3 Users Say Thank You to Functional Artist For This Useful Post:
Hellion (07-09-2019), mckutzy (07-09-2019), Panhead5496 (07-11-2019)
  #2  
Old 07-09-2019, 10:08 AM
mckutzy mckutzy is online now
Senior Member
 
Join Date: May 2008
Location: bc, canada
Posts: 7,155
Thanks: 783
Thanked 1,702 Times in 1,398 Posts
Default

This is cool... Ive been waiting for someone to do a writ up on this... I actually forgot about these.....
I was going to get one of these awhile ago... I was going to see if I can rig it to the blower housing to take reading off of the flywheel magnet..... but the HE sensor needs to read a certain magnetic polarity for use...

I found that itll work based on the measurements given.. in theory that is... but Im curious as to your input of these....

In the search on these devices... I found that people have used them for all sorts of rpm reading things, cause its really self sufficient; mount, apply magnet, maintain gap, apply power.....
A Cool one I saw, was for a drill press, just mounted to the quill and was able to get a really good reading...

---------- Post added at 09:08 AM ---------- Previous post was at 09:06 AM ----------

A secondary question to above......
With this device how much of a fuse value would you need to use? say in a stand alone or even automotive use?
__________________
10yr+ club..... My current ride- http://www.diygokarts.com/vb/showthread.php?t=5461
Reply With Quote
The Following User Says Thank You to mckutzy For This Useful Post:
Functional Artist (07-09-2019)
  #3  
Old 07-09-2019, 10:55 AM
Functional Artist's Avatar
Functional Artist Functional Artist is online now
Senior Member
 
Join Date: Jul 2016
Location: Toledo, Ohio
Posts: 1,772
Thanks: 678
Thanked 684 Times in 535 Posts
Default

Quote:
Originally Posted by mckutzy View Post
This is cool... Ive been waiting for someone to do a writ up on this... I actually forgot about these.....
I was going to get one of these awhile ago... I was going to see if I can rig it to the blower housing to take reading off of the flywheel magnet..... but the HE sensor needs to read a certain magnetic polarity for use...

I found that itll work based on the measurements given.. in theory that is... but Im curious as to your input of these....

In the search on these devices... I found that people have used them for all sorts of rpm reading things, cause its really self sufficient; mount, apply magnet, maintain gap, apply power.....
A Cool one I saw, was for a drill press, just mounted to the quill and was able to get a really good reading...

---------- Post added at 09:08 AM ---------- Previous post was at 09:06 AM ----------

A secondary question to above......
With this device how much of a fuse value would you need to use? say in a stand alone or even automotive use?
Hey mckutzy

Looks like it
...but, I dunno, were gonna find out.

As far using as a fuse,

According to the specs:
..."Power requirement: DC 8-15V
...& Proximity output current: 200mA"

Kinda small values
...& the diagram doesn't show a fuse
...so, I gonna skip it (for now)

But, to answer your question, in an automotive situation it looks like 12VDC will power it fine
& probably a 12V 1A - 3A automotive type fuse should be adequate protection
__________________
RESISTANCE IS FUTILE
Reply With Quote
  #4  
Old 07-09-2019, 12:56 PM
mckutzy mckutzy is online now
Senior Member
 
Join Date: May 2008
Location: bc, canada
Posts: 7,155
Thanks: 783
Thanked 1,702 Times in 1,398 Posts
Default

In this case what would be the proper power supply, wire gauge to use? 12ga?
__________________
10yr+ club..... My current ride- http://www.diygokarts.com/vb/showthread.php?t=5461
Reply With Quote
  #5  
Old 07-09-2019, 08:35 PM
itsid's Avatar
itsid itsid is online now
Moderator
 
Join Date: Jul 2013
Location: Ruhrpott [Germany]
Posts: 9,774
Thanks: 1,333
Thanked 4,154 Times in 3,103 Posts
Default

the meter itself draws maybe 200mA (I'd say closer to 100 tbh)
the proximity sensor doesn't need 300mA at all
(maybe for 300kHz but that'd equate to 18 million rpms and I haven't seen anything that spinny yet )
It might still draw the full amps though (totally unneeded for the task at hand)
I use Honeywell 495As hall sensors and they can be powered by the chips output pin (20mA or less) and are still quite responsive .. at least good enough for something like such tach
something with an internal comparator makes more sense for such task,
but I only have smd parts (salvaged off a bldc cd-rom motor)
5mA good for the 30k rpm the bldc is able to run at [model escapes me atm]

Anywhoo, four seven segment led ~10mA per segment I guess..
makes 70mA per digit.. 280mA max..
usually they use pov so no more than three leds are on at once (30mA per digit... makes 120mA) especially since that saves a led driver chip and all leds can be powered of the microprocessor directly (which I guess can provide no more than 200mA in total)

Sooo at worst that thing draws 500mA;
I'd say the chip and stuff draws 15mA maybe 20.. the display should be good with less than 150mA and so it all comes down to the proximity sensor... if it actually draws 300mA or is cool with 50mA [as it should])

So in total I assume something like 250mA or less (depending on the number displayed)
So awg 20 should do really; 16 if you want to dial in on the safe side

Fuse.. a 500mA quick should protect all internals but I doubt it'd be needed really.

'sid
__________________
Jokes about german sausage are the wurst.
Reply With Quote
The Following User Says Thank You to itsid For This Useful Post:
Functional Artist (07-11-2019)
  #6  
Old 07-09-2019, 11:19 PM
mckutzy mckutzy is online now
Senior Member
 
Join Date: May 2008
Location: bc, canada
Posts: 7,155
Thanks: 783
Thanked 1,702 Times in 1,398 Posts
Default

Im really not that knowledgeable in the electronic field, I just know everything is needs to have certain things in a fashion or things burn up... But thanks for breaking it down....
I kinda understand...

This is cool... So even a/couple of 9v batteries could do the trick with out a fuse???

FA- what kinda things were you thinking about using this for???
__________________
10yr+ club..... My current ride- http://www.diygokarts.com/vb/showthread.php?t=5461
Reply With Quote
  #7  
Old 07-11-2019, 11:16 AM
Functional Artist's Avatar
Functional Artist Functional Artist is online now
Senior Member
 
Join Date: Jul 2016
Location: Toledo, Ohio
Posts: 1,772
Thanks: 678
Thanked 684 Times in 535 Posts
Default

Quote:
Originally Posted by mckutzy View Post
Im really not that knowledgeable in the electronic field, I just know everything is needs to have certain things in a fashion or things burn up... But thanks for breaking it down....
I kinda understand...

This is cool... So even a/couple of 9v batteries could do the trick with out a fuse???

FA- what kinda things were you thinking about using this for???
Yup, that was a really good/in-depth analysis, Thanks Sid.

I gonna set this (1) up as a mobile/hand held style meter
& run it off of a (1) 9V battery

Kinda like the hand held Amp/Volt meter I assembled during/for use with El Turbo
http://www.diygokarts.com/vb/showthread.php?t=36894
(the meter part starts @ post #51)

I mainly want to use it to get some RPM data on these MY1020 & ZY102 motors
...then, ???
__________________
RESISTANCE IS FUTILE
Reply With Quote
  #8  
Old 07-11-2019, 02:23 PM
Functional Artist's Avatar
Functional Artist Functional Artist is online now
Senior Member
 
Join Date: Jul 2016
Location: Toledo, Ohio
Posts: 1,772
Thanks: 678
Thanked 684 Times in 535 Posts
Default

Here is the meter (front & back)

I did some measuring (it looks like ~2 3/4" x 1 3/16")
& marking (used a pencil & a square)

* I'm using another piece of plastic from an old TV back
& gonna use a small plastic box for the back cover

** I did all of the marking & cutting on the (smooth) back side
...so, if I messed up/slipped & scratched the surface it wouldn't be visible on the (textured) front side

*** I also put a scrap piece of cardboard on the work bench
...as to not scratch the front side, while I'm workin' on the back side
Attached Thumbnails
SAM_1707.jpg   SAM_1708.jpg  

SAM_1709.jpg   SAM_1710.jpg  

SAM_1711.jpg   SAM_1712.jpg  

SAM_1716.jpg   SAM_1717.jpg  

SAM_1718.jpg  
__________________
RESISTANCE IS FUTILE
Reply With Quote
The Following 2 Users Say Thank You to Functional Artist For This Useful Post:
landuse (07-12-2019), Panhead5496 (07-11-2019)
  #9  
Old 07-12-2019, 06:18 AM
Functional Artist's Avatar
Functional Artist Functional Artist is online now
Senior Member
 
Join Date: Jul 2016
Location: Toledo, Ohio
Posts: 1,772
Thanks: 678
Thanked 684 Times in 535 Posts
Default

The back cover/box is ~2" x 3" x 2"
...so, the display, a 9V battery & an on/off switch should fit inside.

Below are the diagrams I drew up

First, I just redrew the (factory) diagram (for quick reference)
...then, I drew a diagram including the battery (power supply) & the (on/off) switch

Notice, the wire colors are no where near consistent
...Chinese ingenuity?

Positive (+) :
red (meter) to brown (sensor)

Negative (-):
black (meter) to blue (sensor)

Signal:
yellow (meter) to black (sensor)

* The switch that I'm using is "technically" a (3) way, on/off/of switch
...but, I'll only be using (2) poles (on & off)

** There wasn't room for the switch on the "face" & to still fit inside of the box
...so, I just installed it (inconspicuously) on the side

*** The display will fill, most of, the front of the box
& the battery, switch & wiring/connections will reside in the back
Attached Thumbnails
SAM_1723.jpg   SAM_1724.jpg  

SAM_1728.jpg   SAM_1722.jpg  

SAM_1720.jpg   SAM_1719.jpg  

__________________
RESISTANCE IS FUTILE
Reply With Quote
  #10  
Old 07-12-2019, 10:44 AM
Functional Artist's Avatar
Functional Artist Functional Artist is online now
Senior Member
 
Join Date: Jul 2016
Location: Toledo, Ohio
Posts: 1,772
Thanks: 678
Thanked 684 Times in 535 Posts
Default

Industrial Velcro secures the 9V battery in place
...but, didn't get any pics

Wiring
I wired the positive (+) battery lead (red wire) to (1) pole of the switch
& then, connected another piece of (red) wire from the other pole to the red/brown wire-junction

The negative (-) battery lead connects straight to the black/blue wire -junction

The signal circuit wires (yellow/black) simply connect together

After shrink wrapping all of the connections I gently tucked the wires into the box
...& then, bolted the face plate to the box, with a couple of 3/16 Allen head bolts/lock nuts


Here is our hand held digital RPM meter

* I mounted the box ~1/2" above the bottom of the face
...so, the meter will sit nicely & it will also hold the display so it's facing upward, just a bit

** Also left some extra plastic, above the display for maybe
...a hole (to hang it on stuff)
...or a clip (to clip it on stuff)
...or ??
Attached Thumbnails
SAM_1728.jpg   SAM_1729.jpg  

SAM_1730.jpg   SAM_1731.jpg  

SAM_1733.jpg   SAM_1732.jpg  

__________________
RESISTANCE IS FUTILE
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 10:50 AM.