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History of MembersPage/GergelyLezsak/SoundCardTrigger
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2016-09-12 09:39:06 . . . . catv-80-98-142-196.catv.broadband.hu [pulldown value: 2k7 recommended]
2009-08-10 13:53:55 . . . . MembersPage/GergelyLezsak [Solution]
2009-08-04 16:07:55 . . . . tls.xs4all.nl [Answer to soundcard issue]
2009-07-31 19:33:29 . . . . MembersPage/GergelyLezsak [Signal gets DC bias from the ecu]
2009-07-31 06:50:26 . . . . kozpont.realszisztema.hu [one tip]
2009-07-30 20:19:56 . . . . om0cb2sr04.adsl.datanet.hu [Asus Eee soundcard trigger strange problem]

Changes by last author:

Changed:
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I had the same problem, some sound cards were working, some not. Every sound card I came across has a DC-blocking cap. The VEMS has a 10k pullup resistor IIRC for HAL-type trigger (VR works fine with every soundcard), making a DC-offset of 5v. The clapming diodes will make the peak value 5v, thus making the DC offset effectively smaller, but if the amplitude of your sound card is to small, it will not reach the '0' level.

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2k7 pulldown recommended on trigger input when driven from soundcard

Changed:
The solution is very simple: Connect a pull-down resistor of the same size as the pull-up resistor in your test cable, thus a resistor from the HAL-input(s) to ground of 10k. This worked perfect on my EeePC 900 and other laptops that weren't working before.
I had the same problem, some sound cards were working, some not. Every sound card I came across has a DC-blocking cap. The VEMS has a pullup resistor making a DC-offset of 5V : (2k7 pullup by default for HALL-type trigger)

* VR usually works fine with every soundcard, but a 2k7 .. 10k pulldown does not hurt anyway

** Note: VR used to have 18k pullup, has 27k pullup since about 2012. The clamping diodes will make the peak value 5v, thus making the DC offset effectively smaller, but if the amplitude of your sound card is to small, it will not reach the '0' level.

The solution is very simple: Connect a pull-down resistor of the same size as the pull-up resistor in your test cable, thus a resistor from the HALL-input(s) to ground of 2k7 .. 10k. This worked perfect on my EeePC 900 and other laptops that weren't working before.

Changed:
* Got it! 10kOhm pull-down resistor to GND worked! (100k not), thanks for your help!
* Got it! 10kOhm pull-down resistor to GND worked! (100k not), thanks for your help!

** 2k7 pulldown is the most universal solution (best for VR or HALL or wheelspeed inputs when driven from soundcard).

** For VR, the pullup usually has no adverse effect if left there (minor attenuation of signal amplitude, and noise also).

** From HALL or wheelspeed inputs: remove the pulldown when driven from real sensor