Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Tachometer driver

Status
Not open for further replies.

MADVAN

New Member
Newbie here that needs help. I have a ford factory tach from a pickup and i have installed it in a van, now i need to calibrate it. The ecm outputs are different. Tach sig comes from a hall sensor and is sq wave 6volt dc.
Pickup output from ecm to tach.
650rpm=43hz/+-10hz 6volt
3000rpm=200hz/+-10hz 6volt
Van output from ecm
650rpm=130hz/+-10hz 6volt
3000rpm=600hz/+-10hz 6volt
I need to convert the 130hz@650 to 43hz@650.
I have nat LM2917N-8 for hz to volt and nat LM231N for the convert back from volt to hz. Seems so far i cannot get the hz out to the spec of 43hz@650rpm with 6volts.
LM2917---vtp=7.56xfreq.inxc1xr1////vtp=7.56x130x.02ufx62k
LM231---freq.out=v.in/2.09xrs/rlx1/rtxct////fout=1.9/2x8k/100kx1/6.8kx0.1uf.
My output is .44volt/3.7hz@650rpm
What did i do wrong I'am stumped, Is there another way to change the hz
any help would be greatly appreicated.
BILL :(
 
Hi Madvan,
Instead of F to V then V back to F, how about simply using a divide-by-3 counter, made from a 4018 and 2 mickey-mouse diodes for an AND gate, that is powered from 6V? Its output isn't a symmetrical square wave, but neither is your LM231, so maybe the tach doesn't care.
 
audioguru
I have looked at sticky's data sheets for cd4017 fairchild. I cannot see how to wire this to divide by three.

BILL :(
 
audioguru said to use a 4018 device -- which is a "divide-by-n" chip. The 4017 is a divide-by-10 device.

**broken link removed** is a datasheet for the TI CD4018B series.
 
audioguru said to use a 4018 device -- which is a "divide-by-n" chip. The 4017 is a divide-by-10 device.

**broken link removed** is a datasheet for the TI CD4018B series.
 
Looks like alot less work this way. Excellent!!!

Going to try the CD4018b with the CD4011b @q1 and q2 for the division of three. Feed to clock is 6v @130hz, my cl out should be 43hz. My question is what voltage will the cl be? Do i have to supply the vdd with 6v so that the vss has a 6v output to feed the cl with a diode? Then i will have my 6v@43hz.

Bill
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top