the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
icon

Tachometers and diodes


Post ReplyPost New Topic
< Prev Topic Next Topic >
volksnut 
Member - Posts: 3
Member spacespace
Joined: January 29, 2006
Posted: January 29, 2006 at 9:11 PM / IP Logged  
I just installed a new VDO tachometer which I must say does not read right....I've tested it against a engine analyzer, when my engine is idling at 800 the tach reads 1200, yes the ground is good, and set at the right cylinders...When driving it flucuates up and down about 300 rpm....I've been told I need to install a diode inline, so I bought a diode from Radio Shack  (IN4004) and installed it, (the package says forward voltage drop is 1.6V and forward current is 1A) it now reads right at idle and up to about 2000 rpm, above that it doesn't follow the engine revs (doesn't want to go above 3000rpm)....did I install to big of a diode...thanks for the help
fingaz22 
Silver - Posts: 410
Silver spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: March 11, 2005
Location: United States
Posted: January 29, 2006 at 9:16 PM / IP Logged  
to small i would say. what kind of car?
JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs
volksnut 
Member - Posts: 3
Member spacespace
Joined: January 29, 2006
Posted: January 29, 2006 at 9:28 PM / IP Logged  
Volkswagen Bus
fingaz22 
Silver - Posts: 410
Silver spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: March 11, 2005
Location: United States
Posted: January 29, 2006 at 9:32 PM / IP Logged  
sorry i need the year and engine also and i will be able to look it up and tell you what the voltage range is for your tach.
JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs
volksnut 
Member - Posts: 3
Member spacespace
Joined: January 29, 2006
Posted: January 29, 2006 at 10:08 PM / IP Logged  
well it's a 4 cylinder 1600cc based motor, vehicle is a 68 , the tach is an aftermarket VDO unit
fingaz22 
Silver - Posts: 410
Silver spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: March 11, 2005
Location: United States
Posted: January 29, 2006 at 10:27 PM / IP Logged  

sorry i figured that is was older. my data base don't go back that far.

but it sounds like your restricting the voltage to the tach. use a dmm and confirm voltage before and after the diode. it should flucsuate with the rpm of the engine.

see what the voltage is before the diode when the engine is above the point the tach stops. and compare with the voltage reading after the diode to the tach. if different(lower voltage after diode) then you will need to upgrade diode. to allow more flow of voltage. if the same and no change in voltage you will need to find out why you are losing voltage.

JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs

Sorry, you can NOT post a reply.
This topic is closed.

  Printable version Printable version Post ReplyPost New Topic
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum

  •  
Search the12volt.com
Follow the12volt.com Follow the12volt.com on Facebook
Thursday, October 31, 2024 • Copyright © 1999-2024 the12volt.com, All Rights Reserved Privacy Policy & Use of Cookies
Disclaimer: *All information on this site ( the12volt.com ) is provided "as is" without any warranty of any kind, either expressed or implied, including but not limited to fitness for a particular use. Any user assumes the entire risk as to the accuracy and use of this information. Please verify all wire colors and diagrams before applying any information.

Secured by Sectigo
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
Support the12volt.com
Top
the12volt.com spacer
the12volt.com spacer