LED Flasher Relay

[hardylt_imp]

For those who do not know how to interpret signals on an oscilloscope I’ll try to give a small explanation.

O-scopes display a voltage that takes place over time. The could be constant DC. Could be AC like in your house. Could be waveforms of all types. In our case here, we will see square waves.

The screen is divided into a grid pattern with horizontal and vertical lines. These spaces between the lines are known as divisions. Each of the divisions has ‘tic’ marks. If you start at a line and count tic marks to the next line you will count 5. The value of the divisions, and thus each tic, will depend on scope settings that the user selects.

The trace on a scope can be positioned on any horizontal line. Or anywhere for that matter. Usually the center line is used to put the trace on with no signal, or 0v. And that is what I did for the pics.

When looking at a signal you must select a voltage range. For instance, 10v. Or actually 10v per division. Voltage is displayed going up and/or down. So if you start at one horizontal line, going to the next line is equal to 10v. Each tic would be equal to 2v as 5x2=10. So 12v will show as one division plus 1 tic. Other voltage levels can be selected.

Time goes from left to right. You select a time base that will show the signal as you want. So, for instance, 5ms (milliseconds) So from one vertical line to the next would take 5ms. Each tic would be 1ms. A pulse that is 1 division and one tic would be 6ms.

In the pics the pulse trains look pretty much the same until you see the time base is different, thus the pulse widths and repetition rates are different. I will point that out with the pics in a following post as I don’t know how long a post can be.
Test equipment: Tektronix TBS 1052 dual trace 50MHz digital scope.

Test setup: Scope probe connected to the left turn signal orange wire in headlight shell. Probe ground lead connected to the ground plate in the left turn signal (easy to get to and the lens was already off).

Bike-battery tender disconnected. Ignition key on, bike not running.

Scope set to 10v per div and 5ms per div.

[url=https://app.photobucket.com/u/everettmclendon/a/a8b5b03b-ad65-49a1-a3d0-f45df1fc2c20/p/75178ebe-275d-493f-aea0-37df9fe25eff]

First, The settings shown should be /division not /cm I had centimeters on the brain last night.

In the pic the running lights are on. The picture shows that they are light by a pulsed 12vdc. The pulses show the voltage is on for 2ms and off for 4ms. Since the voltage is not a constant 12v they are dimmer than they would if fed a constant 12v.

[url=https://app.photobucket.com/u/everettmclendon/a/a8b5b03b-ad65-49a1-a3d0-f45df1fc2c20/p/36df8cf5-894b-45b6-9822-c698cc4dee01]

The above pic is with the left turn signal selected.
The scope is set to 10v/div and 500ms/div

The turn signal light flashes by the voltage turning on and off (obviously) It is on for ~400ms and off for ~300ms or on about .4sec and off for .3 sec.

You can see the pulses are 12v as they are 1 division high plus 1 tic. That is 10+2=12

Any mistakes blame PB

Fascinating! Thank you for that investigation LPG. Couldn't have asked for a more in-depth explanation. And I appreciated the crash course in oscilloscopes as well.

The flicker makes more sense now. 2ms is nowhere near enough time for the sweeping pattern on my LED's to complete. And, the whole LED array doesn't flicker--only the first diode in the pattern. So if I understand it correctly, every 6ms or so it's just constantly trying to begin that flash pattern, with never enough time to complete. And so instead I get a rapid flicker on the inside corner of both signals. Mystery solved.

I imagine if it was a more typical LED signal with a uniform flash pattern, not sweeping, the running light power would possibly translate into a more useable low-level illumination. Or at least all diodes would flicker together? But overall I get the sense that 2-wire LED's are probably just not intended to function as both DRL's and turn signals in that way. Seems like that's what 3-wire LED's are for.