mike_va

The other one looks regulated also, with a simple 3 terminal linear reg? Hard to tell about the VR1, because it is in a box. Will they send you schematics? How much current do the PIR's take? As long as they are fairly low (<100mA total) I would go with the linear reg. Assuming just a simple linear reg doing some rough number crunching, 24VAC rectified will be less than 36VDC (I'm being lazy with the math) and at 100mA this would be (36-12)*0.1=2.4Watts on that heatsink which is probably around 20C/W or something like that so you should be fine. Try it out when you get it, if you can touch the heatsink it is less than 50C (call it a rule of thumb...). If you think you are going to need more current I'd call them and ask if the other is a switcher. The other (unlikely) issue would be ground loops, I'm not familiar with those PIR's but if relay contact outputs (i.e. isolated) like my Honeywell's should not be a problem. Have not spent alot of time looking at this but hope this helps. Mike

It is a little more difficult to design a good switcher, but they can actually have a longer lifetime if done correctly due to the lower losses. Heat directly impacts lifetime, to get 15 years for example in a space application we usually derate to 105C max junction temp etc. Perhaps when he said not a good option he meant there was no in house expertise or money to allocate to development. Most people do not understand magnetics and control loops well enough to cobble a switcher together, and the comment about low cost might refer to using certain parts that will not have enough derating to have good reliability, low EMI etc. There are definitely more subtleties to designing a switcher than using a standard 3 terminal linear reg (which is pretty resilient and tolerant of a wide range of design practices). The other inherent advantage is that you are not limited to the input current. For example to make the math easy 44V 0.1A (current limit) available, linear reg you can get 12V 0.1A and must dissipate 3.6W. Switcher you can get 12V 0.367A assuming no losses, or if we say 95% then losses are 0.22W. Having said that all these cameras that run off 44V POE must have a switcher inside, to step it down to voltages that logic level parts like to see. Even my Bosch Dinion (non-POE) is spec'd to run off something like 10.8-39VDC (in addition to 28 VAC) or something like that. I have it hooked up to a HP variable lab supply. As the voltage is increased the current goes down as expected with a switcher (i.e. roughly constant power). The other advantage switchers can give (not all though) is isolation, which has bearing on both grounding and various fault and environmental situations. Lastly someone could try to argue that a switcher (especially based around POE) is slightly less reliable just based on the increased part count compared to a linear reg. Nearly everything has a switcher these days however and they can be designed to be very reliable (although perhaps less so if someone tries to save the last few cents). The major players can sometimes save the last few cents but to do this successfully there is usually a pretty rigorous qualification program behind it all.

Don't use a 7812 at 1A, input voltage is too high at 48V (35V max) and power dissipation will be too great (48-12)*1A=36W not gonna happen. Even a fairly large heatsink at 1C/W would put you at a 36C rise, too hot to touch. You could make a more complicated linear circuit but this is not the way to go. Most designs do this with switchers, that way you can also increase the output current to greater than the input at lower voltages. Look at it as power in and out.

I know in space (satellites) this can actually happen...depends on the resistivity of the material. In some orbits/cases additional shielding is provided over the wire insulation to prevent it from getting charged. Wires that are not connected can build up charge and actually discharge/arc. I mention this just because it is kind of interesting. ESD containers are not made of perfectly insulating material, so they will not hold a charge. I don't think that's what is going on here though...reversing the static does not make sense... Just the act of touching the wire would dissipate any possible charge.

I have an Axis P1344 which I just bought, because I have a P3344 that works well for the front driveway with the lights that are outside of the house. The P1344 is just sitting inside, pointing out the back window to cover the walk up basement. I've just started playing with this and placement is not final. I cropped the pic on the right side, the yellow box is just what triggered the capture. Outside there is a Lorex IR camera mounted under the porch, I discovered it's IR light would be picked up by the P1344 at night. As a result it actually sees much better than the Lorex at night. However, the focus changes. If I adjust it at night it is not in focus during the day. Do I need a different IR-type lens? The Lorex does not seem to have this problem, although it is not a high resolution camera (P1344 or even some CNB's I've been playing with surpass easily). It has the lens that came with it, Tamron megapixel auto iris. Thanks, Mike

This was a very good guess. As it turns out, these were some of the first models and they were NOT IR corrected. Now have some Computar megapixel lenses that Axis sent, these do not have the problem. Attached are the focus positions with the IR filter on and off, nearly identical. Thanks to everyone for the help!

Either that or an artifact of taking a screen shot of the 2400 using the clip function on a mac. I could not figure out how to freeze it easily, there is no snapshot function like on some of the other axis.

darkness

You can use ultravnc server on windows 7 to access it on a mac using chicken of the vnc. Works great. I've use realvnc with windows xp and chicken also. Basically makes that window show up on the mac, it's great. I have my system on windows and access it that way. These are free programs.

Axis has responded that this is an IR corrected lens. I've sent my server report as they requested so we'll see what they can figure out.

Maybe so, they've opened my ticket so we'll see what they say. BTW, I have a second (new) P1344 that I was trying not to open. It does the same thing.

I've done this for our security system. Kinda brute force: tapped in to a logitech mouse for the contact closure, use the logitech software to hit a python script to send a text message. Sends a text when armed or alarm goes off. Alternatively you could use the demo version of vitamin d to send a picture when it detects a person. Mike

Nope, the 1344 is CS type. The 3344 is built into the camera (dome). They spec out the same though so I assumed (again) same electronics different packaging.

No, not unless the lens is IR corrected. In a cheap lens, even red, green, and blue within the visible spectrum will focus differently. I guess that makes sense. I had started this experiment with a P3344, which does not have this effect. I assumed that the P1344 would be similar performance but in a box camera. I'm using the lens that came with the P1344 (Megapixel Tamron). I guess that is a possibility although disappointing if true. I'll ask Axis when the get back to me. I just tried the same experiment on the P3344, it auto-focuses on almost the exact same spot with the filter in and out. For the adjustment I used the advanced tab and the same focus box for each case.

Tried it on a different scene. The focus settings are different depending on whether the filter is enabled or not.

Shouldn't the color have roughly the same focus?

Maybe a depth of field issue? This is what I'm used to seeing with a camera with the aperture open, is this similar for the iris (which is open at night)? Please let me know if I'm not looking this the right way. Also it is windy (and cold) here perhaps a smidgen of blur? I think I'm at the limit of what I can think of to try. Thanks for the help, Mike

Christopher, thanks for the response, I even broke down and read the manual. I've eliminated IR, I have the same problem using a flood light outside (PAR incandescent) and I've eliminated the window. So I'm just manually switching it back and forth using the IR filter select of the camera. I'm almost starting to wonder if there is a camera defect? You can hear a whirring when it switches, perhaps the are adjusting the backfocus and this was not calibrated right? Or took a hit in shipping or? Axis has not responded to the support request yet but it is the weekend. Thanks again, Mike P.S. Some of the Axis don't look that good spec wise at night, I have an older 2120 and it sees nothing (as one might expect from the lux rating). On the other hand I have a CNB BBM24F and a VCM24F and they are better at night than the P1344. I can use the P3344 on the front of the house, but can't use a shutter speed higher than 1/30s at night.

Further experimentation with another lens (Tamron Varifocal Auto-Iris) yielded the same results. Also, the lens I thought was not tight might have been. It appears the lens once tightened down will still rotate.

This represents focused in b&w, then switched to color:

Yep, I'm still not there yet. Tonight the camera is outside, no IR just one flood. Switching it back and forth using the IR cut filter. Can't get it focused in both. When it is focus amazing, just what one pays all this money for... The first two represent focused in color, then switch to b&w.

Well, tonight it does not seem as bad but it is still there to an unacceptable amount (case tried through the glass and with IR present). Switching from color (via flood light) to b&w it is STILL unfocused in b&w. However, if I hit the autofocus in b&w it is then OK but going back to color it is unfocused...

Well, I figured out why I could not see the shutter settings. On this camera you have to set exposure priority to motion then they appear. Indoors today the problem did not seem as bad, then I discovered a few important things: 1 - the lens despite looking nice on the camera was not screwed down all the way. Rotated perhaps another 45 degrees. (Edit - I now realize it may have been screwed down, but will continue to rotate) 2- engaging/disengaging the IR cut filter you hear a click then a faint whirring (the latter you have to have your ear right next to the camera). Perhaps this is automatic back focus. And perhaps at night looking through the window it was not working well. With the lens tightened down it stays in focus pretty well looking at an indoor scene (i.e. not through glass). I really appreciate all the forum help getting me this far. Filled out a ticket with Axis but they have not gotten back to me (although in fairness it is Thanksgiving weekend so was not expecting a lot). Tonight will perform more experiments.

Pictures from this morning, through the window. B&W I manually set the IR filter to OFF and it is in focus.

Pretty much the same, you can manually focus though. This amount of delta in focus is surprising, I'd rather leave it in night mode but for this amount of money...