Hi Gibson,
good to see you're keen. as long as you're willing to put in the time and effort you'll get this working fine. FYI I haven't actually finished mine yet, I had to put this project on hold shortly after the last post. I've had a few other things come up but am hoping to get back to it within the next couple of months
With making it look good, that's not quite as hard as you might think. check out the project forum on this site. it's for custom built PC's. it might not be what you're interested in, but allot of the fabrication work is very clever, and I'm getting allot of ideas from it.
what kind of car is it for? FYI the temp ckt works great, so does the PWM, haven't tested the fuel ckt yet and I'm using the tach ckt for the speedo too.
feel free to either keep posting here or PM me if you want to know more (and I know you will )
good to see you're keen. as long as you're willing to put in the time and effort you'll get this working fine. FYI I haven't actually finished mine yet, I had to put this project on hold shortly after the last post. I've had a few other things come up but am hoping to get back to it within the next couple of months
that vwvortex link is actually where I got the diagrams and some good help from the original poster there for my Tach guage. FYI, that tach schematic is designed for the VW golf, there's a few typo's on that diagram that meant I spent allot of time getting very frustrated trying to understand why it wasn't working. . it can be allot simpler than what's there. also one problem I found with that circuit is heat. the 3914's get very hot, where they really shouldn't be producing much heat if working efficiently.
With making it look good, that's not quite as hard as you might think. check out the project forum on this site. it's for custom built PC's. it might not be what you're interested in, but allot of the fabrication work is very clever, and I'm getting allot of ideas from it.
what kind of car is it for? FYI the temp ckt works great, so does the PWM, haven't tested the fuel ckt yet and I'm using the tach ckt for the speedo too.
with the dimmer, I too had the same questions, but Wook's suggestion for using PWM ckt is much better, you can have all the seperate guage ckts and the + side of all LED's goes through the PWM, so the brightness of all LED's is controlled by the one PWM ckt.i found a guy who used a single lm3914 to make a VERY basic tach for his car, and it looks like dimming the LEDs at night will be a pretty simple affair based on his schematic located about 1/2-way down the page. my question is - will i need a copy of his "section for headlight auto-dimmer" for each individual 3914, or can i just feed all of them from just one circuit? I plan to have a total of 10 lm3914's in my new gauge cluster: 3 for tach, 3 for speedo, 2 for vacuum/boost, and 1 each for fuel level and coolant temp.
it is possible to make it flash, and switch from dot to bar mode. I've attached the datasheet for the lm3914. check out the example ckts. second pic page 12 and first pic page 13. the frequency at which the LED's flash could probably just be change with the cap/res combo you see in that example (pg 13.)One other question - when using the 3914 in bar mode, apparently you can wire it up so that the whole display will flash when a specific led comes on. This would be ideal as a shift light in the tach, or as posted earlier, a warning light for over-temp. or maybe even a warning for when you're speeding. my question is, do you simply reduce the size of the capacitor in the flash circuit to make it flash faster, and if so, how much should you reduce it by to get something like a 4-6hz flash?
I haven't tested the fuel guage ckt yet, and can't remember if that issue was discussed but I do remember thinking about it.one last comment... my factory fuel gauge is fluid-damped, so it simply can't move quickly - most cars seem to be this way, causing it to take 2-3 minutes to move from E to F when you refuel. is there any way to "damp" or average the signal coming from the float in the tank so that when fuel is sloshing around in there, the fuel gauge isn't wildly oscillating? for anyone else who's already done this, is this even an issue?
feel free to either keep posting here or PM me if you want to know more (and I know you will )
Attachments
-
812.9 KB Views: 12