SPC900 LXmod yesyes style ;-)

[malc-c]

Reggie,

Not sure of these links help explain the LX amp off mod... it seems to apply to the sensor rather than web cam model

Cosmicshed: ICX414AL Amp-Off Modification

Most of the info gleaned was from Steve Chambers web site Intro

But also found this, which seems to suggest the amount of amp glow is voltage related rather than an ON OFF requirement

Direct Bias Amp Off Experiments for SC1 and SC3 modified Toucam webcams

Hope that helps

[yesyes]

Ah... Now I get it. The AmpOff transistor switches the 11V Zener parallel to the 15V Zener on the camera PCB, therefore reducing the 15V supply to the CCD to 11V. That Q3 on the PCB must be the regulator for the CCD 15V supply.

Thanks for those links, Macolm

[yesyes]

With regard to the 2nd transistor, We know that we can do pin inversion using an ftdi chip and this can be written to the chips internal eeprom, so we don't need the inverter transistor but as the 2nd transistor is only switched on when our pin gets switched and our pin would be at 5v it tends to suggest that the 2nd transistor is unecessary as well.

I don't think so (with regards to the 2nd transistor). I think it does not just supply a high or low signal but it switches through an (unknown) signal from one PCB to the other (or disconnects that signal).

I do agree on the 1st transistor though. If you have a way of guaranteeing that you will always have an inverted signal available, you could get rid of it. But how much is an additional transistor and a resistor? I rather keep that transistor and have peace of mind..

[Reggie]

Many thanks for posting Malcolm, I agree that it's about the reduction of voltage to the CCD but I don't think the DTR pin circuit achieves that.

[malc-c]

Many thanks for posting Malcolm, I agree that it's about the reduction of voltage to the CCD but I don't think the DTR pin circuit achieves that.

No, but my guess is that when DTR is made high, that then turns on the transistor, which parallels up the zener as described in YesYes's post above

[Reggie]

I don't think so (with regards to the 2nd transistor). I think it does not just supply a high or low signal but it switches through an (unknown) signal from one PCB to the other (or disconnects that signal).

I do agree on the 1st transistor though. If you have a way of guaranteeing that you will always have an inverted signal available, you could get rid of it. But how much is an additional transistor and a resistor? I rather keep that transistor and have peace of mind..

with the ftdi chip you program the pin inversion into eeprom on the chip.

Have you tested your amp-off circuit yet? Could you post the results please?

[RogerTheDodger]

I had my LX cam handy so I've just tested the amp off with a 300s image and see no difference... I'll have to scope it out to make sure it's actually working - this is with the serial transistor circuit.

[Reggie]

Ok, so I am now happy with the DTR circuit in general, someone built me a model of the circuit so that I can see how it works, my only question now is, is an 11v zener diode low enough voltage to affect the amp-glow significantly?

Rogers initial test seems to suggest not, all references to the amp off circuit that have been posted seem to talk about lowering the voltage somewhere between 6-9v when the circuit is on.

[RogerTheDodger]

I unmounted my other LX webcam to see if that is working and the amp mod makes a big difference - I now know that the amp off mod is not switching on my other cam now, but it's set in the off mode so I'll leave it alone...

Amp off and amp on, 300s exposures.

[Reggie]

Hi Roger, many thanks for testing your other modded cam, it's much appreciated, I believe these are the first test results posted for this particular mod on here. This gives confirmation that amp-off does work in this circuit, despite my reservations

Many thanks to chris and Malc too for digging out information to clear up any issues and also to my friend who RE'd the circuit, persevered with my ignorance:iamwithstupid: and showed me a simulation of the circuit working.

Roger, if you ever decide to look at your other webcam to see why the amp-off circuit doesn't work, i'd be very interested in your findings.

Sorry if anyone thought I was like a dog with a bone on this point, my major concern was that it wasn't working or wasn't working as well as it could be, especially given the number of people that have done this mod and the likelyhood of some of those cameras getting sold on in the future.

I think Roger just goes to show that it's worth testing your mods and sharing results just for your own piece of mind at the very least.

Once again, thanks to all involved

[yesyes]

Agreed. Thanks for testing, Roger. I didn't have the time yet to test with one of my own modded cams.

However, it seems there is still a bit of amp glow left, even with the mod. When I get around to it I will test with a lower voltage zener and see if that makes a difference. Unless someone else is quicker testing this...

[Gina]

I'll see what I can do. Still waiting for a clear night to do any observing or imaging but that wouldn't stop me trying the webcam (if I can work out what to do) SharpCap recognises the modded webcam but haven't checked it. I've only used the standard mode so far.

[DIYASTRO]

Glad to see those pics of reduced amp glow! Good work Roger.

Just to let interested people who obviously look at this very interesting thread that I have just tested another 'YES YES' build which incorporates a GPUSB within the camera. Have yet to try this in an actual guiding capacity but the pc recognises the 4 way hub, Usb serial converter, camera, and gpusb. The build also has the 5 volt fan which I have used in my 4 mods to date and all seems to work well. The idea of the GPUSB within the camera housing is again, to reduce the need of two usb cables from pc to guide scope. The GPUSB RJ plug simply comes from the camera to the scope mount.

Boyd

[Reggie]

Hi Boyd, I'm wondering how much heat is being generated squeezing more and more things inside the same box? Dont' get me wrong, I think all of these mods are great, just mindful sometimes of the impact that all this has.

Just to show I'm not getting down on the idea of squeezing more into the box, here's a 7 port version of the yesyes hub for you all (this one is powered too!!)

PC Laptop 7 Ports USB 2.0 Powered HUB + Free AC Adapter | eBay

[DIYASTRO]

OOOP's Just began to run the configuration from my last post and it looks like the GPUSB is trying to draw too much power! Camera image begins to flicker, fan reduces in revs / speed and then camera refuses to respond!

This is only on a short USB lead too, so... has anyone tried to 'link in' a seperate 5v power supply to the YES YES circuit? My thinking is that leaving the negative conections to the hub board from the pc intact but removing the positive and adding the extra current via dc cell. Anyone tried this? (May have to be done via an opto isolator circuit)

Boyd

[Gina]

Just to show I'm not getting down on the idea of squeezing more into the box, here's a 7 port version of the yesyes hub for you all (this one is powered too!!)

PC Laptop 7 Ports USB 2.0 Powered HUB + Free AC Adapter | eBay

Yes, I've got one of those I bought a few years ago. I'll use it at the mount if the 4 way one I've got runs out of ports. I'm at the limit now with EDDIR, imaging webcam, finder webcam and GPS dongle.

[DIYASTRO]

Reggie:Looks like a 'solution' but would this still only provide 500mA? Even with the power adaptor.(I will order a couple though, they look usefull!) I think what I am looking for is adequate power at the camera end without danger of voltage / current spike coming back to the pc. With regard to fitting it all in one box... I follow your reasoning but if sufficient power was available several fans could be used to cool. Perhaps I am simply going over the top with the idea of single usb cable!

Boyd

[Reggie]

It should provide 500ma per port on the hub, although it's probably (just guessing) a 2amp power supply that comes with the 7 port hub, so it won't give 500ma on all 7 but you should get away with most of the stuff you need with 2amps, unless of course it's a 3.5a+ DC adapter.

I'm not sure which thread I discussed it in but I have a different 7 port hub that is powered, it should really have a schottky diode between the 5v DC in and the usb 5v, it doesn't it has a 0ohm jumper resistor but it seems to work OK, without hurting the PC. With the PSU each port should in theory be able to draw 500ma, in practice it's only a 2amp dc adapter but that's more than enough for what we're doing really.

Now don't take my word on all of this as gospel, I haven't tested anything, I have talked to a few people that know their beans, so I'm confident that my 7port hub and psu are working fine (they could be better with more caps in place to smooth out plugging/unplugging but that's a whole other story).

It sounds like there shouldn't be an issue removing the 5v from the usb from the pc and replacing it with the 5v from your DC in and not sure entirely why you think an optoisolator would help here

From what I've seen of 'yesyes' hub and the 7 port ones in his power box mod, they all use the same usb chip (FE1.1 I think) and are all setup as if they are being externally powered, of course if you remove the usb 5v and replace it with a connection to the DC 5v then it will only ever work with the DC adapter.

[Gina]

The PSU with the one I've got says 5v 1000mA so nowhere near enough to power 7 ports fully (enough for only 2 at the full 500ms)!! May do a bit better than an unpowered one but not by much. If I use that hub I'll probably provide my own 5v supply.

Come to think about it, I'm wondering if I'm suffering from low power at the hub - I get occasional USB problems.

[DIYASTRO]

Reggie

One of the reasons that I am so interested in external dc supply for usb hubs is that;

a) eventually want to build obsy with no 'permanent' mains power (all run from UPS modules with lots of big batts. Only using mains supply to keep batts in charged condition)

Never been keen on any mains powered electronic unit being used in the dark / damp at night

c) so many mains power failures where I live in the winter that mains is not a reliable option

d) the best time to observe / image if weather is suitable, is during a power cut! No light pollution!

So, since all my equipment to date is mains power free I would like to keep it that way. If the psu that comes with the 7 port hub is a simple regulated 5v dc high amp supply then that should be ok. (providing each of the ports gets its share)My concern was that the dc 5v in the usb connection was somehow neccessary for some of the data transfer. I dont know if this is the case or not, perhaps you could clarify this?

I have no objections to adding a skt to the camera to take external voltage supply as long as it is from portable source with no psu's involved.

The idea behind the opto isolator was to reduce any risk of external voltage / amp spike going back to the pc, again perhaps not neccessary if the usb voltage isnt connected anyway.

Boyd

[Reggie]

Gina, I would suggest measuring the voltage on your existing DC adapter, and then getting a higher amperage DC adapter. I know 2amps doesn't cover all 7 of my 7 port hub, I get the feeling they're not expecting these things to be used by astronuts in fields That having been said, as long as my power draw is below the 2amps then I should be able to utilise all 7 ports, there is nothing managing current to the 5v line on the hub ports.

Boyd, yes, you can replace it with a voltage regulator, but it may or may not be 5v, it's quite possible it's 5.25v but that depends on whether there is a diode to seperate the usb 5v from the DC 5v, an optoisolator is no good for this circuit If the 7port hub does have a schottky diode separating the supplies, the unit will need 5.25v I would have thought to account for the voltage drop across the diode (it will be low, something like 2-300mv) if you feed it 5v with the schottky then it will likely take the 5v voltage below usb spec.

I've measured mine and it's 5.25v but as previously mentioned, on my 7 port hub where there should be a diode, there is a jumper resistor, it still works.

Please don't anyone take what I am saying as being the last word, it's entirely possible that that there are subtle differences between the various versions of hubs that we're using, I know of 3 versions of my 7 port hub and they're all slightly different in their own ways but all of them use the same family of usb chip (FE1.1 or 1.2 I think).

[Reggie]

Hi all, anyone managed any further testing on the amp-off circuit yet?

I'm going through things with wxastrocapture, sharpcap and phd guiding, just wondering how people go about using and testing in either of these apps? What do you consider optimal settings? What is your testing process for proving the Long exposure mod works?

For instance, wxAstrocapture 1.81 has inverted logic as default, as such the mod won't work 'out of the box' unless of course you remove the inverting part of the RTS long exposure circuit (first transistor and it's resistor) so my first observation is that you need to untick 'inverted logic' in wxAstrocapture in options, settings on the LE control port tab. If I don't I just get a black screen.

In sharpcap, the opposite is true for me, I have to tick invert for the RTS pin, with wxAstrocapture and sharpcap I can I can easily see that the mod is working, increasing the exposure time increases the brightness of the image eventually leading to total blowout (white video image).

PHD on the other hand doesn't seem to have any logic inversion settings and I don't seem to be getting any long exposure from it at all. Which has me very puzzled right about now, I'm adjust the LE read delay but nothing showing yet, no difference in the image, it's as if I'd set it to 5fps.

Anyone care to do some testing on wxAstrocapture, sharpcap and phd for me?

[DIYASTRO]

Reggie

I am just having a look with the wxastrocapture, not sure which version I have!

I am not sure why but I seem to get the increased brightness with increase in exposure time regardless of the inversion of the rts.

Select camera is SPC900NC640-480(YUY2)

Properties set as Brigh 50 / Gam 50 / Gain 50 I can choose frames per sec 5-30 and exp 1/25-1/10000

Option LE control is on Com port 5 And it makes no diference if I invert logic when I switch camera to LX with on board switch

Boyd

[RogerTheDodger]

Reggie, what do you want tested? be aware there is a bug in PHD on the serial port setting in the version that is is on Craig's website, I have a later version that I can make available to you but I don't want to publicly post it without Craig's permission.

[Reggie]

not sure really how to define a decent test. wxAstrocapture without doubt needs me to switch off inverted logic, so testing that would be a good start.

In wxAstrocapture and sharpcap My gain, gamma, are all set to their lowest setting and fps is set to 5, exp 1/25th, awb and ae are off. Exposure length anywhere between 0.6s and 4 seconds should be a reasonable test, with and without logic inversion settings.

Boyd, that's odd, it should work one way and not the other.

Roger, if you could PM me about PHD that would be fantastic.

It seems that wxAstrocapture and sharpcap are working but have different definitions of 'inverted logic' and phd may well have the serial bug that roger describes.