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About Mr.RC-Cam

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    RC-Cam Mentor

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    R/C, FPV, Embedded Programming, Electronic Design.

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  1. That sounds unusual. I would expect that even with a dead battery your scope would still be able to finish the self cal test. But I don't know for sure. Your scope is a different animal because you have the 2245 and mine is a 2245A. Regardless, my best advice is to start by confirming the power supply voltages are correct.
  2. Announcements and motor rev's are pre-recorded wave files stored on a SD card. The Audio Player is controlled by the Arduino. Details: https://github.com/thomastech/CAN2Cluster/tree/master/WaveFiles
  3. The arduino code is available here (Aug-08-2017 post): https://www.rc-cam.com/forum/index.php?/topic/4139-diy-rf-power-vswr-meter-low-cost/&do=findComment&comment=29002
  4. If you look through the HeadPlay HD Goggle Upgrade discussion you will see a photo of a SMT board created by a forum member. Maybe the photo will give you some inspiration.
  5. The most common choice is to use the Boscam RX5808 module. It is very low cost and widely available. There have been reports that the RX5880 has slightly better performance. However I don't believe that the bare RX5880 module is readily available. If you can't find a supplier then the workaround would be to purchase a FR632 and unsolder the modules in it. Not sure if this is worth the effort, that decision is up to you.
  6. They are not open source hobby projects. Instead, they are proprietary designs. So the manufacturer does not publish the schematic. This is suppose to prevent the competition from cheating by cloning their work, but rarely stops the problem. A determined person can create the schematic by reverse-engineering the device. It's a lot of work to do that accurately. A lot of cloned products are bad copies.
  7. I cannot offer any specific advice on changing the video level of the FS or IRC module. I would need the video circuit schematic before offering a solution.
  8. On paper, the specs are similar. But in reality, the newer modules have proven to perform better. Range testing shows RF sensitivity has increased. Also FS/IRC compatibility with other brands has improved because the original Airwave modules used different video de-emphasis. De-emphasis on the NexWave is now similar to the other Chinese brands. Correcting the video level is the responsibility of the external circuitry. Before 5.8GHz was introduced it was common to find a video level adjustment POT either inside the module or externally on the main PCB. No, they did not solve the reason for the video level POT. Instead, the designers decided that reducing their manufacturing costs was more important than giving us accurate video levels. Some FPV users that are suffering bad performance are unaware that their video issues are due to incorrect video amplitude. This problem continues to be ignored and it is difficult for the average FPV consumer to troubleshoot.
  9. The original FatShark (FS) and ImmersionRC (IRC) 5.8GHz modules used vRx modules with the Taiwanese Airwave chip. They were limited to seven channels. Airwave's published video bandwidth was approximately 5.5MHz. But in practice it was typically less than 5MHz. All the current FPV 5.8GHz vRx's (including FS and IRC NexWave modules) have the Chinese Richwave chip. It supports a 5725 - 5865 MHz frequency range. Its SPI mode allows controlling the frequency with a couple MHz resolution. So that is why so many operating frequencies are possible. As far as I know Richwave does not publish a video bandwidth specification. But I think it is safe to assume that the bandwidth remains the same on the various frequencies. The practical video bandwidth will depend on the module's implemented design, component placement (board layout), and build quality. So you will have to measure your module to determine its real video bandwidth. I suspect that most modules offer something between 4 MHz to 5 MHz.
  10. The RTC6618 is a RF amplifier chip. It could be used with a 5.8GHz FM demodulation chip (i.e., RTC6715 or similar) to help increase range. I don't see the datasheet for it on the Richwave site. I don't know if ImmersionRC's NexWaveRF module uses a RTC6618. You'll have to open one up and look inside. - Thomas
  11. Check https://groups.io/g/TekScopes for repair tips and advice on your TEK 7104.
  12. Congrats, the WiFi modification is complete. Enjoy!
  13. You'll need a 6-inch (15cm) long RG316 coax cable with SMA receptacle connector. For convenience I suggest purchasing a RG316 SMA extension and cutting off the plug end. Like this: Also needed is a SMA equipped 2.4GHz omni dipole antenna with +2dBi to +3dBi gain. Avoid those cheap Chinese antennas, they often have reduced RF performance. By the way, you can use RP-SMA connectors instead of traditional SMA. But never mix RP-SMA with SMA. Disassembly: Remove the left side panel (5 screws) and the bottom panel (6 screws). Pry off the menu knob. Remove the rotary encoder board (4 screws) and transparent LED lens insert (2 screws). Remove the LCD bezel trim screws (4 places). Remove the front bezel trim. There is some hidden sticky tape holding it down, so slowly pry it off to prevent damage. Unplug the two I/O cables. Pull out the LCD board. Note: The existing antenna is a PCB microstrip located on the LCD PC Board. See image below. We need to cut it away and then add the external antenna. PC Board Copper Trace Cuts: Use a sharp knife and scratch off a small rectangular area of solder mask near C17 to expose the copper ground plane. Solder tin the GND area. See photo below. Use a sharp knife and CUT the Antenna's feedline trace from the C7 coupling cap. See photo below. Use a magnifier and visually inspect the CUT. Next use an ohmmeter and confirm it's no longer electrically connected to the nearby pad on C7. Coax Installation: The RG316 coax is prepped (cut signal and shield, pre-tin conductors) and then soldered to the PC board. The center conductor goes to C7 and the shield goes to the GND area created in the previous step. See photo below. Note: The 6-inch length is long enough to reach the left side panel. Avoid longer coax lengths to minimize RF signal attenuation. Thoroughly clean off the flux residue. Add some hot melt glue to strain relieve the coax. Do this away from the RF circuitry; The open area between C15 and R9 is a good place. When you re-install the LCD board just pass the coax (with SMA receptacle connector) through the existing opening that is used for the board's two I/O connectors. No need to cut or drill the LCD's mounting bracket. Antenna / SMA Mounting: Mount the SMA connector on the front-left side of the metal base. You can drill a hole in the metal panel, but I printed a new side panel instead. The location of the SMA connector is shown in the photo below. Validate the mod: Test it out. You should notice that WiFi range is dramatically improved. If not, then you've made a mistake; Check your work again.
  14. Last month (Feb 2019) I purchased a refurbished MP Select Mini V1 3D Printer for $89 USD (with free shipping). The flash price quickly ended, sold out. After the unboxing I found that mine was new (not refurbished). But I had to replace the extruder's cooling fan because it was too noisy. Monoprice did not respond to my email request for a replacement part. Fortunately I had a 12VDC 30mm fan that fit, so problem solved. I quickly discovered that WiFi connections were unreliable. For the record, it works fine when the printer is close to the router in my living room closet. But I need to print elsewhere. And the short range is understandable because the WiFi antenna is inside the printer, surrounded by the heavy sheet metal case. The solution is to convert the printer to use an external antenna. Before I talk about my antenna hack, I would like to point out that there is a fantastic wiki site that discusses a variety of mods for this printer. It includes instructions on how to enable WiFi connectivity, which is a hidden (unadvertised) feature of the V1 printer. I recommend that all MP Select Mini owners bookmark the Wiki: https://www.mpselectmini.com/start With all the formalities out of the way it's time to talk about the Wi-Fi antenna modification. Let's start with some fine print. It's not a hack for the typical mortal. Things to consider: It voids the warranty. Blame only yourself if things don't go as planned. Altering RF circuitry is not like working on a traditional DC circuit. In the RF domain *everything* matters. Good SMD soldering tools and PCB rework experience is a prerequisite. This hack is difficult/risky so proceed with caution. You've been warned. Before you start the modification, first confirm that your printer's WiFi is working. I shouldn't need to say this since the mod is for users that are unhappy with the RF range they are currently getting. But some hackers like to do mods just for the sport of it, so that's the reason for advising to fully test it out before any hacking.
  15. Most of the details to the video signal are lost with a 1MHz scope. But in my experiment, the bottom of V-Sync and peak white amplitude were present, so a crude measurement was possible. Don't purposely purchase a cheap digital scope if you intend to do video measurements. But if you already own it, then try this: First use it to observe a good (calibrated) NTSC or PAL video signal. If the 1Vpp amplitude measurement appears valid then you will have confidence that it can be used to measure/calibrate a bad video signal.
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