---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 10/20/17: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:54 AM - Re: Constructing an automatic RCA video camera feed splitte (Eric Page) 2. 10:13 AM - Re: Re: Constructing an automatic RCA video camera feed splitte (Alec Myers) 3. 10:38 AM - Re: Constructing an automatic RCA video camera feed splitte (Eric Page) 4. 03:36 PM - Inexpensive voltage data logger (GTH) 5. 04:53 PM - Re: Inexpensive voltage data logger (Alec Myers) 6. 04:59 PM - Re: Inexpensive voltage data logger (Robert Borger) 7. 05:06 PM - Re: Re: Constructing an automatic RCA video camera feed splitte (Robert L. Nuckolls, III) 8. 11:32 PM - Re: Inexpensive voltage data logger (Eric Page) ________________________________ Message 1 _____________________________________ Time: 08:54:10 AM PST US Subject: AeroElectric-List: Re: Constructing an automatic RCA video camera feed splitte From: "Eric Page" alec(at)alecmyers.com wrote: > I think were ok. That section is either wrong, or badly written, I cant work out what its trying to say either. But: > > Look at table 1 in para 8.4 - control L gives High-Z at the output. True, and that line of Table 1 is the most recent item on the revision history. However, the second paragraph of the intro (Sec 3, pg 1) and paragraph 8.1 (pg 14) are consistent in their description of the outputs; that is, tied to either Vdd when Vc is high, or to Vss when Vc is low. I presume "high" means Vc = Vdd and "low" means Vc = Vss; that's certainly what many of the diagrams suggest. If, as Bob says, the NTSC signal we're working with is DC biased and exists entirely above 0V, then we can use a single supply and it shouldn't be an issue. That will simplify the schematic, shrink the BoM and ease the layout. There are apparent errors elsewhere in the datasheet as well. Fig 5 (pg 9, Typical ON Characteristics) includes a wiring diagram that shows -- as you would expect -- Vc = Vdd. However, Fig 9 (pg 10) depicts the test setup for this measurement and it shows Vc = Vss = -5V. Then Fig 10 (pg 11, OFF Switch Input or Output Leakage) shows exactly the same setup, with Vc = Vss. Apparently the outputs can be ON or OFF with the control high or low. This must be a quantum device! This datasheet is a mess. I guess we stand by for results of Bob's test with a sample camera, and Wade's test with multiple cameras through a switch... Eric Read this topic online here: http://forums.matronics.com/viewtopic.php?p=473706#473706 ________________________________ Message 2 _____________________________________ Time: 10:13:10 AM PST US From: Alec Myers Subject: Re: AeroElectric-List: Re: Constructing an automatic RCA video camera feed splitte The code is 90% done. Ill do the other 90% in due course. On Oct 20, 2017, at 11:53, Eric Page wrote: alec(at)alecmyers.com wrote: > I think were ok. That section is either wrong, or badly written, I cant work out what its trying to say either. But: > > Look at table 1 in para 8.4 - control L gives High-Z at the output. True, and that line of Table 1 is the most recent item on the revision history. However, the second paragraph of the intro (Sec 3, pg 1) and paragraph 8.1 (pg 14) are consistent in their description of the outputs; that is, tied to either Vdd when Vc is high, or to Vss when Vc is low. I presume "high" means Vc = Vdd and "low" means Vc = Vss; that's certainly what many of the diagrams suggest. If, as Bob says, the NTSC signal we're working with is DC biased and exists entirely above 0V, then we can use a single supply and it shouldn't be an issue. That will simplify the schematic, shrink the BoM and ease the layout. There are apparent errors elsewhere in the datasheet as well. Fig 5 (pg 9, Typical ON Characteristics) includes a wiring diagram that shows -- as you would expect -- Vc = Vdd. However, Fig 9 (pg 10) depicts the test setup for this measurement and it shows Vc = Vss = -5V. Then Fig 10 (pg 11, OFF Switch Input or Output Leakage) shows exactly the same setup, with Vc = Vss. Apparently the outputs can be ON or OFF with the control high or low. This must be a quantum device! This datasheet is a mess. I guess we stand by for results of Bob's test with a sample camera, and Wade's test with multiple cameras through a switch... Eric Read this topic online here: http://forums.matronics.com/viewtopic.php?p=473706#473706 ________________________________ Message 3 _____________________________________ Time: 10:38:08 AM PST US Subject: AeroElectric-List: Re: Constructing an automatic RCA video camera feed splitte From: "Eric Page" nuckolls.bob(at)aeroelect wrote: > Bob, I'm having trouble making sense of this graph. I read the National Instruments page (http://www.ni.com/white-paper/4750/en/) it comes from, but I'm not sure I've got it straight. See if this sounds right... The Y axis ("IRE") is a somewhat arbitrary unit. That is, zero IRE is "usually 0V" but (by implication) it doesn't have to be. The zero-reference and blanking level in the signal is set by the "back porch" following the horizontal sync pulse, so any DC offset within reason is automatically compensated by the nature of the format. As long as the signal is pretty close to 1V pk-pk, it doesn't matter if it's centered on 0V -- or, as we're proposing, on 2.5V -- the zero point is wherever the "back porch" sits. So, if you find a signal from your test camera that's riding somewhere between 0V and 3.3 or 5V, and we power the CD4066 from a single 5V rail, we should be in good shape. Since the IRE scale spans -40 to +120 in the NTSC format, and an NTSC signal is supposed to be 1V pk-pk (into 75 ohms), then you could say that 1 IRE = 12.5mV. Is that in the ballpark? Thanks! Eric Read this topic online here: http://forums.matronics.com/viewtopic.php?p=473711#473711 ________________________________ Message 4 _____________________________________ Time: 03:36:50 PM PST US From: GTH Subject: AeroElectric-List: Inexpensive voltage data logger Hi all, For troubleshooting purpose we would like to log the bus voltage on our project. I was directed to this product which seems quite suitable : https://www.maplin.co.uk/p/maplin-usb-dc-voltage-data-logger-n70dp Unfortunately they don't ship outside the British Isles. Does anyone know a more easily available device ? Thanks in advance, -- Best regards, Gilles http://contrails.free.fr http://lapierre.skunkworks.free.fr ________________________________ Message 5 _____________________________________ Time: 04:53:27 PM PST US From: Alec Myers Subject: Re: AeroElectric-List: Inexpensive voltage data logger Ill be in the UK second week in November; I can bring one back for you, if you can wait. Theres a more sophisticated thing with wifi called a Mooshimeter, but its expensive. Also Adafruit might have a variety of parts you can use/program. On Oct 20, 2017, at 6:35 PM, GTH wrote: Hi all, For troubleshooting purpose we would like to log the bus voltage on our project. I was directed to this product which seems quite suitable : https://www.maplin.co.uk/p/maplin-usb-dc-voltage-data-logger-n70dp Unfortunately they don't ship outside the British Isles. Does anyone know a more easily available device ? Thanks in advance, -- Best regards, Gilles http://contrails.free.fr http://lapierre.skunkworks.free.fr ________________________________ Message 6 _____________________________________ Time: 04:59:05 PM PST US From: Robert Borger Subject: Re: AeroElectric-List: Inexpensive voltage data logger Giles, Here=99s what is available on Amazon: https://smile.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&fie ld-keywords=voltage+data+logger If would be happy to purchase one of them for you if you can not buy it from France. Blue skies & tailwinds, Bob Borger Europa XS Tri, Rotax 914, Airmaster C/S Prop (75 hrs). Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP 3705 Lynchburg Dr. Corinth, TX 76208-5331 Cel: 817-992-1117 rlborger@mac.com > On Oct 20, 2017, at 5:35 PM, GTH wrote: > > > Hi all, > > For troubleshooting purpose we would like to log the bus voltage on our project. > > I was directed to this product which seems quite suitable : > > https://www.maplin.co.uk/p/maplin-usb-dc-voltage-data-logger-n70dp > > Unfortunately they don't ship outside the British Isles. > > Does anyone know a more easily available device ? > > Thanks in advance, > > -- > Best regards, > Gilles > http://contrails.free.fr > http://lapierre.skunkworks.free.fr ________________________________ Message 7 _____________________________________ Time: 05:06:21 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Constructing an automatic RCA video camera feed splitte At 12:37 PM 10/20/2017, you wrote: > > >nuckolls.bob(at)aeroelect wrote: > > > > >Bob, I'm having trouble making sense of this graph. I read the >National Instruments page (http://www.ni.com/white-paper/4750/en/) >it comes from, but I'm not sure I've got it straight. See if this >sounds right... > >The Y axis ("IRE") is a somewhat arbitrary unit. Yeah, it's dimensionless . . . like dB in audio, it describes a ratio of voltages for video painting a max white, black, blacker-than black, burst amplitude and sync amplitude. >That is, zero IRE is "usually 0V" but (by implication) it doesn't >have to be. The zero-reference and blanking level in the signal is >set by the "back porch" following the horizontal sync pulse, so any >DC offset within reason is automatically compensated by the nature >of the format. I think I understand your assertion . . . I've seen various ways for video to be transported on a DC stable reference. The time base correctors I used to build had three points of dc restoration as the signal progressed through the system. One is advised to do this so that variations in gross video energy don't manifest as momentary blooms or potholes in observed luminance. You can find video being managed at various voltage levels, 1 v pk-pk in 75 ohms was adopted for shipping video around studios and stations on coax. This is equivalent to the legacy "0 VU" in audio systems being pegged at about 1.25 vrms across 600 ohms. On further reflection (it's been 30 years or so) I decided to refresh my recollection about the 1 v pk-pk number. Found this little diddy on RS-170, the industry convention for television signals. http://tinyurl.com/382a25m According to this paper, the 1v value was originally crafted in the black-n-white days where 1v = 100 IRE RS-170 was the original "black-and-white" television signal definition, per EIA. The original standard defined a 75 ohm system and a 1.4 volt (peak-to-peak, including sync) signal. Signal level specifications form RS-170 were: White = +1.000V; Black = +0.075V: Blank = (0V reference): Sync - -0.400 Volts. In this world, the conversion would be 10Mv/IRE Read more at: http://www.epanorama.net/documents/video/rs170.html So after you took a 'clean' white level of 100 IRE and added 40 IRE of sync, you had a 1.4 volt pk-pk signal in 75 ohms When color came along, the various levels of luminance from black to white COULD be enhanced with some hue and saturation of COLOR carrier that might add another 40 IRE to the white level. So add sync to that and you're up to 180 IRE or perhaps 1.8v pk-pk. It will be interesting to see how the cameras are supplied. Most monitors are able to accept and accurately display signals from 0.5 v pk-pk to perhaps 4 volts . . . after all, it's just a 'volume control'. The the ratio of elements in the audio stream remains the same irrespective of actual power or transmission impedance. IRE is video analog to audio VU or DB. >As long as the signal is pretty close to 1V pk-pk, it doesn't matter >if it's centered on 0V -- or, as we're proposing, on 2.5V -- the >zero point is wherever the "back porch" sits. > >So, if you find a signal from your test camera that's riding >somewhere between 0V and 3.3 or 5V, and we power the CD4066 from a >single 5V rail, we should be in good shape. > >Since the IRE scale spans -40 to +120 in the NTSC format, and an >NTSC signal is supposed to be 1V pk-pk (into 75 ohms), then you >could say that 1 IRE = 12.5mV. > >Is that in the ballpark? Yup, the cameras we're looking at are fitted with coaxial termination that is, no doubt, intended to work smoothly with the constellation of video products in a 75 ohm world. It will be interesting to see what the cameras give us. Bob . . . ________________________________ Message 8 _____________________________________ Time: 11:32:55 PM PST US Subject: AeroElectric-List: Re: Inexpensive voltage data logger From: "Eric Page" I've played around with one of these a bit and it seemed to work quite well. http://preview.tinyurl.com/ya7pg9sg I do believe it has to be plugged into a computer at all times while operating; I don't think you can just set it up and power it from a dumb USB power supply. Eric Read this topic online here: http://forums.matronics.com/viewtopic.php?p=473727#473727 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.