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  • Garmin & Samsung Charger Reverse-Engineering

    It has 5 wires:Red with inline fuse (750mA 250V) goes to +8~32VDCBlack = groundYellow = Serial data outWhite = Serial data inGreen = Serial groundI'm hoping the serial ground can just be tied to battery ground. I'm just about to begin cutting the plastic away from the main circuit board. I will also look for any sign of a resistor inside the USB Mini-B connector on pin 4, though it could be back on the main board

    13 sub pages for Garmin related pinouts, nothing that explains what I am trying to do. They have just the one page: http://pinoutguide.com/GPS/garmin_nuvi_power_pinou...But they do not indicate how Garmin uses the data pins, so it's an incomplete pinout. Adequate for building a charging cableAccording to one source I've seen, pin 2 is RX, pin 3 is TX. Garmin has several serial port emulation modes. On my GPSMAP64, in the systems settings is a menu for the USB mode. List of choices includes 'Garmin Spanner', 'Garmin Serial', 'NMEA in/out', 'Text out', 'RTCM', 'MTP'MTP was a new one for me. That's 'Media Transfer Protocol', a Microsoft proprietary mode as far as I knowThe cable I have is meant for the NMEA mode, to connect chart plotters and other marine gearWhat I'm interested in is the ...

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    13 sub pages for Garmin related pinouts, nothing that explains what I am trying to do. They have just the one page: http://pinoutguide.com/GPS/garmin_nuvi_power_pinou...But they do not indicate how Garmin uses the data pins, so it's an incomplete pinout. Adequate for building a charging cableAccording to one source I've seen, pin 2 is RX, pin 3 is TX. Garmin has several serial port emulation modes. On my GPSMAP64, in the systems settings is a menu for the USB mode. List of choices includes 'Garmin Spanner', 'Garmin Serial', 'NMEA in/out', 'Text out', 'RTCM', 'MTP'MTP was a new one for me. That's 'Media Transfer Protocol', a Microsoft proprietary mode as far as I knowThe cable I have is meant for the NMEA mode, to connect chart plotters and other marine gearWhat I'm interested in is the RTCM mode. That allows the GPS to accept DGPS correction signals. Of course Garmin, in their inscrutable wisdom, has skipped providing any details in their public documents to state just how that works. Like what message types are used by the unit? What baud rate? They only say that it's a SC-104 format, but I can't find any copies of that standard anywhere without forking over a credit card and spending the last of my money just to find out if the document even helps me

    ISL 4221 is a RS-232 receiver/transmitter. USB side has 5 wires to the board. I just checked all of them with a meter. Pin 1 = Red, Pin 2 = White, Pin 3 = Green, Pin 4 = Yellow, Pin 5 = BlackThere appears to be a resistor directly between pins 4 & 5. Simply measuring from where the wires attach on the board I see 12.11KΩ between the yellow & black. Black wire does not connect directly to the ground plane, there's another device grey instead of black. I think it's a capacitor. Nothing to test that withYellow wire, pin 4, also has a trace running from that resistor to a small transistor, which in turn connects to a larger transistor that is tapped right into the red wire for a power connection. So something interesting happening thereI'm not doing much more with this, as I'd...

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    ISL 4221 is a RS-232 receiver/transmitter. USB side has 5 wires to the board. I just checked all of them with a meter. Pin 1 = Red, Pin 2 = White, Pin 3 = Green, Pin 4 = Yellow, Pin 5 = BlackThere appears to be a resistor directly between pins 4 & 5. Simply measuring from where the wires attach on the board I see 12.11KΩ between the yellow & black. Black wire does not connect directly to the ground plane, there's another device grey instead of black. I think it's a capacitor. Nothing to test that withYellow wire, pin 4, also has a trace running from that resistor to a small transistor, which in turn connects to a larger transistor that is tapped right into the red wire for a power connection. So something interesting happening thereI'm not doing much more with this, as I'd rather try bypassing the entire board for my data connection and I might even just use another voltage regulator for outboard powerThe large transistor, something right next to that which disappeared, a resistor and one of the inductors are all broken off the board. Lets just call this a $30 angled USB Mini-B pigtail and just move on!

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  • Garmin & Samsung Charger Reverse-Engineering

    Somebody ought to start a wikipedia page detailing every combination out there for the USB Mini-B. Assuming more people chip in with additional entries, eventually that could result in small start-ups & us DIY enthusiasts having a better idea of which layout works for what. Maybe there's good reasons to complicate the interface? Be nice to know why a voltage divider is used on the Samsung instead of a single resistor tied to ground. I have a inline USB volt/amp meter. That tool really shows some differences in what otherwise looks to be just a pile of cables. Now I'm thinking it might be nice to get that breakout board to find out more about all my OEM cables. Just purchased a $30 Garmin data/power cable for their Mini-B based devices, because nobody has any solid info on how that's...

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    Somebody ought to start a wikipedia page detailing every combination out there for the USB Mini-B. Assuming more people chip in with additional entries, eventually that could result in small start-ups & us DIY enthusiasts having a better idea of which layout works for what. Maybe there's good reasons to complicate the interface? Be nice to know why a voltage divider is used on the Samsung instead of a single resistor tied to ground. I have a inline USB volt/amp meter. That tool really shows some differences in what otherwise looks to be just a pile of cables. Now I'm thinking it might be nice to get that breakout board to find out more about all my OEM cables. Just purchased a $30 Garmin data/power cable for their Mini-B based devices, because nobody has any solid info on how that's wired. If I see it uses a simple circuit network, I should describe that here

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  • GPS - Cables, Power & PC Sync

    It would be nice to include Garmin's USB Mini-B, 5-pin connectors. I've been looking for any info on how Garmin uses this type of connector. Most people say that this port requires a serial to USB adapter. But, Garmin states that the port can be set to operate in a 'virtual serial port mode', I've seen one pinout that suggests the ID pin (pin-4) is tied to VCC (pin-1) and possibly this triggers an automatic changeover in some of Garmin's units. That could be wrong. The reason I am looking into this, is that I want to use a 3DR type radio modem to transmit DGPS corrections from my own base station, to a GPSMAP64. And to do so in a very compact & lightweight rig that can be carried out in the forest. So preferably only one single battery pack to run both the radio modem and the handhe...

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    It would be nice to include Garmin's USB Mini-B, 5-pin connectors. I've been looking for any info on how Garmin uses this type of connector. Most people say that this port requires a serial to USB adapter. But, Garmin states that the port can be set to operate in a 'virtual serial port mode', I've seen one pinout that suggests the ID pin (pin-4) is tied to VCC (pin-1) and possibly this triggers an automatic changeover in some of Garmin's units. That could be wrong. The reason I am looking into this, is that I want to use a 3DR type radio modem to transmit DGPS corrections from my own base station, to a GPSMAP64. And to do so in a very compact & lightweight rig that can be carried out in the forest. So preferably only one single battery pack to run both the radio modem and the handheld GPS, with a serial datalink connecting the two. Base station is: https://emlid.com/reach/ with this antenna: https://www.ebay.com/itm/High-Precision-GNSS-GPS-G...Using a free data stream from a local CORS monitoring station, without the handheld, just for testing purposes - I am currently getting a GPS fix with an accuracy of about 3mm in all three axes. It would be nice to have the same location accuracy while bushwhacking property lines where line-of-sight is not possible

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  • Home Made Ultrasonic Cleaning Tank

    Two years late, but maybe for anyone else who might be wondering the same thing. According to one industry expert, energy absorbed by tank walls has a greater effect in the smaller tank sizes, for example: 5-gallon tank= 250 watts RMS, 80-gallons= 2kW. I would recommend looking at commercially made tanks with the size you need, then finding out what they used for system wattage. But you will need to be careful if the particular manufacturer is using peak-power, or average power. The ultrasonic signal is an alternating waveform and in order to compare power between any two systems, the average or RMS power should be used.Size of cavitation bubble determines the cleaning effectiveness. The larger the bubble is, the greater it's impact force when it collapses. Signal frequency relates to h...

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    Two years late, but maybe for anyone else who might be wondering the same thing. According to one industry expert, energy absorbed by tank walls has a greater effect in the smaller tank sizes, for example: 5-gallon tank= 250 watts RMS, 80-gallons= 2kW. I would recommend looking at commercially made tanks with the size you need, then finding out what they used for system wattage. But you will need to be careful if the particular manufacturer is using peak-power, or average power. The ultrasonic signal is an alternating waveform and in order to compare power between any two systems, the average or RMS power should be used.Size of cavitation bubble determines the cleaning effectiveness. The larger the bubble is, the greater it's impact force when it collapses. Signal frequency relates to how far a molecule of cleaning solution is moved before the signal half-cycle allows it to move back, thus becoming a 'collapsed cavitation bubble'. System wattage relates to how well the cleaning solution is loaded in order to perform work, but it is when there is an absence of input energy when the actual cleaning action takes place. ie, on every half-cycle when the power signal hits zero amplitude. Generators operating at 25kHz work well for removing heavy paint layers from rugged parts like cast-iron. 37kHz is a good general-purpose frequency. 45kHz works better for more delicate parts, polished surfaces and soft base materials like what is found in carburetors

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  • Crystal cMoy Free Form Headphone Amplifier

    I think it might be better, now that I thought about it some more, to either use a SSR instead of a mechanical relay to cut down on the time it takes to shut down power, or to wire a mechanical relay with a blocking diode so it energizes with correct polarity and block power to the amp until the relay has time to trip

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  • Crystal cMoy Free Form Headphone Amplifier

    In series with that back-biased diode, add the coil of a relay. The coil will limit the amount of current passing through the diode. Then, have the relay break the power connection to the rest of the circuit and maybe light-up a red LED to show the fault condition.

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