XL500 sample timing

I have tried these mods on my sea hunter xl 500 and the only one that gives a slight stronger depth is the 12k changed to a 5k mod...all the rest of your ideas guys does not work 1.2n and the irf740 only creates unwanted noise and a loss of about 30% sensitivity/depth....any other ideas please

hi there

has anybody done any of these mods ...that we can try for th xl 500....more info needed please

[Mrand]

Sorry, whether somebody has problems with the sight?

[homefire]

Is that akin to the Drop Kick Test?

[Eugene52]

XL500 sample timing

If it ain't broke, Don't Fix it!!!


My last famous words.

IF IT IS AN INTERMITTENT PROBLEM , THEN HIT IT WITH A BIG HAMMER , A STEADY PROBLEM WILL BE EASIER TO FIX !!!!

[homefire]

Been busy and sorta sick! Time to start this up again!

Glade to see the site is back too!

[homefire]

Yep! I made that mistake on some coil wires one time !

I've never done that

If it ain't broke, Don't Fix it!!!

But, take pictures of how it looked and how you took it apart if you do.

[homefire]

If it ain't broke, Don't Fix it!!!


My last famous words.

[Qiaozhi]

Why does copy/paste work some times, but not others? It's not simple, it's whimsical. Is there some special technique? I am lost



Ctl+C, Ctl+V works within this window, and from this window to my computer, but not from my computer to this window.

It's probably because the image is accessible from the web, but if you cut and paste from your machine, then it can only be seen locally.

[porkluvr]

clarification

You will need different transmit pulse duration (RC timing at the 555 ) when switching to IRF740.

After doing some more quantitative (virtual) analysis, what I meant by that statement is that if you replace the BJT with IRF740 (making appropriate bias resistor changes, of course) but leave the original RC components on the 555, you will see about 11ma increase in current consumption. Counting only the transmit section, that's about 11% or 12% increase and, well, that might be OK, but...

You can simply parallel 100k across the 8.2k resistor between pins (2,6) & 7 to put current consumption approximately back to where it was. Transmit PPS increases about 10%, from the original ≈100, if my memory serves me.

The two circuits I showed in the post from which the quote was taken were selected based on their using extremely common resistor values, not because they are particurlarly special.

I reloaded my OS last night, and even though I had seperate partitions for OS and data - the reformat procedure went horribly amuck. Now, I am testing a new piece of software.
It's called R-Studio. I think the "R" stands for "Recovery", as in 'data "Recovery"'.

I'm sort of glad the HD in jeoprody is "only" 300GB.

[homefire]

Time for work here soon. I need to read your last post when I'm not so tired.

I use PhotoBucket.

Hyperlink to the photo.

If I Delete the photo in PhotoBucket, the link will show nothing but a error code.

Yes Stock Coil is unshielded. I think I will try other stuff before messing with the 555.

Need to take it out in the field and see what it dose too!

[porkluvr]

He did it like this ->



A simple copy and paste.

Why does copy/paste work some times, but not others? It's not simple, it's whimsical. Is there some special technique? I am lost



Ctl+C, Ctl+V works within this window, and from this window to my computer, but not from my computer to this window.

[porkluvr]

I am glad your machine is working after being operated on. YOU, LUCKY!

I have some other -conservative- ideas for modification. I do not think you would be wise to try and copy Carl's Hammerhead timing setup - not until you have replaced the BJT with a IRF740. Don't do it, you will very likely fry your output!

You should try and make sure you do not push your output BJT beyond its stock configuration power level.

Attached are some possible timing mods. If you have an unshielded coil (that's my guess), you may run into problems using high transmit frequencies. 388Hz is not exactly lightning fast, and so it might work better than your original 100Hz. Either of these two scenarios will transmit slightly lower power compared to your stock unit, so your BJT should survive.

You will need different transmit pulse duration (RC timing at the 555 ) when switching to IRF740.

You should learn to use LTspice, it's free. The XL500 transmitter timing circuit is relatively fool-proof to set up and run. MJE3055 and IRF740 models are not included with LTspice but I could supply them and help you get started.
Of course, the 555 timer model (and all the others) are not exactly accurate compared to a real world device, and maybe I rely too heavily on simulation data, but hey - it beats zilching a component or two and not knowing why! Or, maybe I'm just funny that way.

With and IRF740; I think your TX signal should decays in about 5us (but don't forget the cable, amplifier overload recovery, etc.). You will probably do well replacing the .0033 cap to shorten the initial sample delay. Maybe .0015 will work? (Keeping your 25kΩ pot and the 5.1kΩ fixed resistor). When you use a different coil, these numbers could all change!

You may get better results if you also reduce sample PW approximately in proportion to sample delay.

NOTE: I did not show the stock configuration in my screenshots. The "Stock... 89ma" is there for comparison against whatever
the i(RSense) value is. I used an extra large filter cap (33mF, 33000uF) and a 1ohm resistor to make it more readily apparent. Also, the two plot panes in each photo use different time scales.

[Qiaozhi]

Hey, how did you insert the dead bug image into the main message??

He did it like this ->



A simple copy and paste.