Re:Re:Show us your homemade Test Equipment
- Wightscope
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I've made quiet a few sensors and get good results.
Some very useful ideas to be found on "gadgets playlist" on YT, I got the stethoscope idea from there.
With a piezo sensor and the range of cheap pressure transducers off ebay (£13/$15) I get some decent results, you just need to build a stable 5v supply - which I did before realizing it would be much easier to use a cheap phone powerpack as they have 5v USB
L-->R, COP sensor, exhaust/intake pressure pulse, stethoscope, 5v supply with an in-cylinder sensor on it - It's also used for fuel pressure with a 100psi sensor, I cut/welded an injector and did in-cylinder on a diesel, cut/welded an HO2S with a 15psi for exhaust back pressure.
Diesel in cylinder (this was a 1000psi sensor so resolution not so good)
Exhaust pulse V8 Jaaag
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- Wightscope
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That is brilliant, must have been in a hurry for it!
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- stevieturbo
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A crank/cam signal generator based on an Arduino nano where you can output various crank/cam signals ( square wave....don't think it offers VR ) and at varying rpm's
The intention of it isn't really universal diagnostics, as it's targeted to a specific project, but obviously it can have generic uses too.
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Sent from my moto g fast using Tapatalk
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"Ground cannot be checked with a 10mm socket"
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I'm really happy with the Nissan Altima refrigerant pressure sensor used as an in cylinder transducer too.
It just has a USB connector I plug right into the Verus USB port for a 5v power supply.
"Ground cannot be checked with a 10mm socket"
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Then there's the less used Pico drain tester. Only comes out when I want to measure draw overnight or longer:
The classic exhaust leak pressure tester! Gauge doesn't work anymore. :blush:
My go-to for COP secondary waveforms. Guts of a Honda distributor, some Amazon cable and Digikey ends.
Last but not least, my test lights! Moe and Joe. Moe got sucked into a fan blade awhile back, hence the mid-coil repair.
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- Wightscope
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@Noah always been a bit wary of connecting any of my home made stuff to a USB port, but that refrigerant sensor looks good.
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- stevieturbo
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Wightscope wrote: Like the vice grip earth. I saw that Eric O does that, seems like a good mod. Looks like you do a lot of parasitic drain testing!
Oh I blatantly stole the vice grip thing from SMA. :silly: After doing that, I can't go back to normal test light clips.
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- Wightscope
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Following an incident today where the fob was showing a transmission on the key fob tester, but as we later found out (post wild goose chase) was transmitting garbage, any ideas for a cheap sensor 315/433.93MHz that would do the trick for a scope... Or I guess I could just pick up a used RF antenna or two
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- Wightscope
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Unlock fobs transmit in response to button push on 315/433Mhz, so far so easy, - get an used antenna for $10 and provide it with power. Watch on scope - in the example mentioned above when the key was tested with an RF tester it was transmitting, but scoping the LIN output from the RF antenna with the button pushed there was a drop of 0.5v, on lock and nothing on unlock, rather than transmission of code 0-12v
The Keyless entry systems/ Passive entry have low frequency transmitters 125-140kHz on the outside of the car in the doorhandles, this effectively acts as a digital finger on the fob so the fob transmits the unlock signal and the car unlocks when the handle is touched.
Keyless start uses the same LF antennas but only inside the car, the key then responds with either an IR or RF broadcast - same frequency as unlock, picked up by same Rf antenna?
In the slot fobs I assume just use the usual transponder technology
So 2 RF antennas 315Mhz and 433Mhz and a 125-140kHz detector for outside should do it.?
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- Wightscope
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Does not appear to be any info available on it - typical! Before I give in and buy another one does anyone have a plug out for similar?
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- Wightscope
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Maybe my theory about any receiver working with any key was wrong.
Unless the lin signal needs to be pulled to high or low at the other end to work.. EDIT Bit of swotting seems to indicate that I need to add a pull up resistor and a diode.
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- Wightscope
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- Wightscope
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A cheap 433 receiver from ebay is next stop , but I do like to re-purpose OEM kit !
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- Wightscope
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- John Curtis
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Making Pressure Differential Sensors (PDA Sensors) for pressure pulse diagnostics.
Currently servicing Central Texas.
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