[Diy_efi] 555 Timer controlled EFI

[Dale Mahan]

Can somebody send me a copy of the schematic for the 555 EFI controller 
- or is it still being designed in-group?

Thank you,

Dale Mahan


Geoff Harrison wrote:

> It sounds like Scotty is using sequential injection. Is your 555 free 
> running, or triggered from ign pulses?
> The simplest freq to voltage converter would be what used to be known 
> as a charge pump, that used in early electronic tachos. It's just a 
> diode feeding an RC network, the meter being connected in parallel to 
> the capacitor. That is a low pass filter. The diode prevents discharge 
> back to the circuit feeding it.
>
> I think the best way to drive the 555 is ignition pulses to the 
> trigger input. This provides compensation for RPM, though it will need 
> a bit of help. The compensation is fed the Modulation pin, which 
> allows the duty cycle to be varied. Throttle position is part of the 
> RC network which sets the pulse width.
>
> So the 555 is fed by freq (ign) and voltage (load) and its timing 
> constant (which is now a variable-TPS)
> (in my scheme)
>
> Geoff Harrison
> ----- Original Message ----- From: <TheEthereal at gmx.net>
> To: <diy_efi at diy-efi.org>
> Sent: Sunday, January 22, 2006 5:56 AM
> Subject: Re: [Diy_efi] 555 Timer controlled EFI
>
>
> The flap-style AFM restricts the intake much more than any other MAF I'm
> aware of. You don't specifically need a F-to-V converter, a low pass 
> filter
> set to the appropiate specs may suffice. Although it's not as elegant 
> as a
> 555. I'm confused by now. What is better to drive the 555 injection, a
> Voltage or a frequency?
>
>> --- Urspr?ngliche Nachricht ---
>> Von: ScottyGrover at aol.com
>> An: diy_efi at diy-efi.org
>> Betreff: Re: [Diy_efi] 555 Timer controlled EFI
>> Datum: Sat, 21 Jan 2006 13:13:16 EST
>>
>>
>> In a message dated 1/21/06 7:13:58 A.M. Pacific Standard Time,
>> kml_daniel at yahoo.com writes:
>>
>> Hi
>> The 555 timer could be used as frequency to voltage converter i   could
>> send
>> you a schematic of it, if you need
>> Kamal Daniel
>>
>>
>>
>>
>> The F-to-V converter was my reply to the person wanting to use the
>> Mitsubishi MAF device. I am using a Datsun Flap-type AFM which has an
>> antilog
>> CFM-to-Voltage curve; I am applying this to pin 5 of a 555 to linearize
>> the  curve.
>> Then processing this signal for Intake air temp. and engine (cylinder
>> heat)
>> temp.; then passing this through a National Semi. A/D device; hen with
>> further
>> processing, this is applied to the input of a programmable 8-bit counter
>> which, through rotary counters, gates, and power transistors, feeds the
>> injectors.
>> Scotty
>>
>