Hi,
I just finished putting together my pulser, and the basic design follows mostly the original circuit from Ron Ingraham, but mine also incorporates the necessary components for the automatic shutdown function in case the battery voltage goes bellow a predetermined value. You can see the circuit I posted with this shortcut:
miwww.com/click?134
I did some preliminary testing of the pulser and at least temperature-wise nothing is heating up much (L1 is barely getting slightly warm to the touch), and the DC current draw is about 60 mA with a pulse width of about 35-40uS (estimated). I can clearly hear the 1KHz whine coming from the circuit, and the LED is lit as soon as the oscillator starts. The pulser has now been left connected to a battery for a couple of hours and nothing blew up so far, another good sign I would say ;-)
In any case the only other test I did so far was to place a 0.1-ohm 5W resistor in series with the negative lead between the negative terminal of the battery and the pulser circuit, and connected a scope across this resistor in order to hopefully able to see the current pulses that goes through the battery. Not sure if this method of testing has any value, and that is the main reason of this post. Hopefully someone more experienced in these matters can either validate my testing procedure, or possibly suggest an alternative. BTW, the battery I'm using for these test is in good shape, I used it for a month in my car without any starting problems or otherwise. The "eye indicator" is always green. I know this only displays the SG condition of one cell, but IMO could be taken as another good indication.
Now, I setup the scope (Tek 2213A) for 2V/Div Vertical, and 0.1uS/Div Horz. Probe is set at X1. Unfortunately I am not able to take a picture of the scope screen, so I will try to explain as clearly as possible the waveform I observed.
What I see on the screen is not a single sharp steep pulse (as seen on many posted photos from other pulser experimenters), but rather a series of pulses close to each other, with progressively lower amplitude. Kind like an oscillation that slowly goes lower in amplitude and then repeats itself. All the pulses of this oscillation have about the same width at the base (about 60nS, or 0.3 div x 0.2uS/div).
The first pulse of the sequence I see on the left side of the screen is always the tallest, it measures about 3.5 divisions, so this would be close to 7V peak. The second pulse happens about 0.2uS later (2 horz div), and has an amplitude of about 2 div, or 4V peak. The third pulse is spaced about 1.6d div after the second, or 0.16uS, and has an amplitude of 1.4 div, or about 2.8V peak. The fourth pulse happens 0.13uS later and has an amplitude of about 1.7V peak. There are about 6 additional smaller pulses after this last one, also spaced about the same horizontal distance between each other, and after this the trace baseline starts to pretty much look progressively flat.
Now, according to ohms law, I=E/R, so in the case of the first pulse to the left the current would be equivalent to I=7V/0.1-ohm, or 70Amps Peak (?). Sounds like an awful lot of current, although certainly of very short duration. But I still wonder if this is correct.
So could someone please validate my tests, or let me know where I'm wrong and explain what really needs to be done in order to get acceptable test data?
Thanks in advance.
-Alex
I just finished putting together my pulser, and the basic design follows mostly the original circuit from Ron Ingraham, but mine also incorporates the necessary components for the automatic shutdown function in case the battery voltage goes bellow a predetermined value. You can see the circuit I posted with this shortcut:
miwww.com/click?134
I did some preliminary testing of the pulser and at least temperature-wise nothing is heating up much (L1 is barely getting slightly warm to the touch), and the DC current draw is about 60 mA with a pulse width of about 35-40uS (estimated). I can clearly hear the 1KHz whine coming from the circuit, and the LED is lit as soon as the oscillator starts. The pulser has now been left connected to a battery for a couple of hours and nothing blew up so far, another good sign I would say ;-)
In any case the only other test I did so far was to place a 0.1-ohm 5W resistor in series with the negative lead between the negative terminal of the battery and the pulser circuit, and connected a scope across this resistor in order to hopefully able to see the current pulses that goes through the battery. Not sure if this method of testing has any value, and that is the main reason of this post. Hopefully someone more experienced in these matters can either validate my testing procedure, or possibly suggest an alternative. BTW, the battery I'm using for these test is in good shape, I used it for a month in my car without any starting problems or otherwise. The "eye indicator" is always green. I know this only displays the SG condition of one cell, but IMO could be taken as another good indication.
Now, I setup the scope (Tek 2213A) for 2V/Div Vertical, and 0.1uS/Div Horz. Probe is set at X1. Unfortunately I am not able to take a picture of the scope screen, so I will try to explain as clearly as possible the waveform I observed.
What I see on the screen is not a single sharp steep pulse (as seen on many posted photos from other pulser experimenters), but rather a series of pulses close to each other, with progressively lower amplitude. Kind like an oscillation that slowly goes lower in amplitude and then repeats itself. All the pulses of this oscillation have about the same width at the base (about 60nS, or 0.3 div x 0.2uS/div).
The first pulse of the sequence I see on the left side of the screen is always the tallest, it measures about 3.5 divisions, so this would be close to 7V peak. The second pulse happens about 0.2uS later (2 horz div), and has an amplitude of about 2 div, or 4V peak. The third pulse is spaced about 1.6d div after the second, or 0.16uS, and has an amplitude of 1.4 div, or about 2.8V peak. The fourth pulse happens 0.13uS later and has an amplitude of about 1.7V peak. There are about 6 additional smaller pulses after this last one, also spaced about the same horizontal distance between each other, and after this the trace baseline starts to pretty much look progressively flat.
Now, according to ohms law, I=E/R, so in the case of the first pulse to the left the current would be equivalent to I=7V/0.1-ohm, or 70Amps Peak (?). Sounds like an awful lot of current, although certainly of very short duration. But I still wonder if this is correct.
So could someone please validate my tests, or let me know where I'm wrong and explain what really needs to be done in order to get acceptable test data?
Thanks in advance.
-Alex
)? I bet you had tested it with below 12V source. So how well it was? Correct me if I was in wrong head. Thx.
