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en:tech:tonohmmeter [2021/01/19 08:38] – bullaren:tech:tonohmmeter [2026/08/12 14:01] (current) – claude
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 ==== Motivation ==== ==== Motivation ====
-{{: tech: tonohmmeter.jpg? direct & 200 | The finished Tonohmeter}}+{{ :media:tech:tonohmmeter:tonohmmeter.jpg?direct&200 |The finished Tonohmeter}}
 Everyone knows the problem that circuits or wiring do not work due to short circuits or interruptions. The domestic multimeter offers a continuity tester that acoustically reveals a low-resistance connection. It only becomes difficult if the location of the short circuit does not reveal itself immediately. A tonohmmeter can be used for such cases. This means that the measured resistance is mapped to the associated pitch. The smaller the resistance, the higher the tone. If the measuring range is sensitive enough, you can get closer to the cause. Everyone knows the problem that circuits or wiring do not work due to short circuits or interruptions. The domestic multimeter offers a continuity tester that acoustically reveals a low-resistance connection. It only becomes difficult if the location of the short circuit does not reveal itself immediately. A tonohmmeter can be used for such cases. This means that the measured resistance is mapped to the associated pitch. The smaller the resistance, the higher the tone. If the measuring range is sensitive enough, you can get closer to the cause.
  
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 ==== Measuring principle ==== ==== Measuring principle ====
-{{: tech: hantek69_1.jpg? direct & 200 | measurement signal}}+{{ :media:tech:tonohmmeter:hantek69_1.jpg?direct&200 |measurement signal}}
 The resistance is measured via the voltage drop. In order to be able to carry out measurements within circuits, a square-wave signal with approx. 340mV (the usual ESD structures of the ICs do not open) is released onto the unknown resistor. The resulting voltage drop is then amplified and rectified via OpAmps. The AVR does the AD conversion and audio output. The resistance is measured via the voltage drop. In order to be able to carry out measurements within circuits, a square-wave signal with approx. 340mV (the usual ESD structures of the ICs do not open) is released onto the unknown resistor. The resulting voltage drop is then amplified and rectified via OpAmps. The AVR does the AD conversion and audio output.
  
 ==== Hardware ==== ==== Hardware ====
-{{: tech: schematic_tonohmmeter.png? direct & 200 | Schematic of the TonOhmMeter}} +{{ :media:tech:tonohmmeter:schematic_tonohmmeter.png?direct&200 |Schematic of the TonOhmMeter}} 
-{{: tech: tonohmmeter_offen.jpg? direct & 200 | The hardware of the tonohmeter}}+{{ :media:tech:tonohmmeter:tonohmmeter_offen.jpg?direct&200 |The hardware of the tonohmeter}}
  
 ==== Power supply ==== ==== Power supply ====
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 The device is only operated via one key (U1). The hardware debouncing (C8 / R3 / R4) avoids the otherwise necessary software. The measuring range is displayed via three LEDs (LED2-4) and the sound output is performed by a small loudspeaker that is capacitively connected to the digital port. That is enough for simple tones. After all, we don't want to output MP3. The device is only operated via one key (U1). The hardware debouncing (C8 / R3 / R4) avoids the otherwise necessary software. The measuring range is displayed via three LEDs (LED2-4) and the sound output is performed by a small loudspeaker that is capacitively connected to the digital port. That is enough for simple tones. After all, we don't want to output MP3.
 ==== PCB ==== ==== PCB ====
-{{: tech: tonohmmeter_pcb.png? direct & 100 | The circuit board of the tonohmeter}}+{{ :media:tech:tonohmmeter:tonohmmeter_pcb.png?direct&100 |The circuit board of the tonohmeter}}
  
 Since I liked the handheld housing from HAMMOND, it was difficult to find a LiPo that was the right size. Unfortunately I only found one for the front, so the board got a bit tight and is populated on both sides. At one end are the two jack sockets for the measuring strips and at the bottom the charging socket with charge indicator. The unused routing area is designed as a ground area. The AVD-ISP connection can be seen on the left, which enables us to do on-board programming. Since I liked the handheld housing from HAMMOND, it was difficult to find a LiPo that was the right size. Unfortunately I only found one for the front, so the board got a bit tight and is populated on both sides. At one end are the two jack sockets for the measuring strips and at the bottom the charging socket with charge indicator. The unused routing area is designed as a ground area. The AVD-ISP connection can be seen on the left, which enables us to do on-board programming.
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 ==== Downloads ==== ==== Downloads ====
-  * {{: tech: Tonohmmeter_v11.c.zip | Firmware Source Code}} in C +  * {{ :media:tech:tonohmmeter:tonohmmeter_v11.c.zip | Firmware Source Code}} in C 
-  * {{: tech: TonOhmMeter_HEX.zip | HEX files for fast programming}} +  * {{ :media:tech:tonohmmeter:tonohmmeter_hex.zip | HEX files for fast programming}} 
-  * {{: tech: Tonohmmeter.pdf | drilling template front side}} +  * {{ :media:tech:tonohmmeter:tonohmmeter.pdf | drilling template front side}} 
-  * {{: tech: Tonohmmeter_bom.pdf | Equipment list (BOM)}} +  * {{ :media:tech:tonohmmeter:tonohmmeter_bom.pdf | Equipment list (BOM)}} 
-  * {{: tech: TonOhmMeter_BOTTOM.pdf | assembly plan back side}} +  * {{ :media:tech:tonohmmeter:tonohmmeter_bottom.pdf | assembly plan back side}} 
-  * {{: tech: TonOhmMeter_TOP.pdf | Assembly plan front side}}+  * {{ :media:tech:tonohmmeter:tonohmmeter_top.pdf | Assembly plan front side}}
  
 ==== Links ==== ==== Links ====
   * [[http://www.heise.de/hardware-hacks/artikel/SMD-Loeten-in-der-Pizzapfanne-1276166.html]] SMD soldering with simple means   * [[http://www.heise.de/hardware-hacks/artikel/SMD-Loeten-in-der-Pizzapfanne-1276166.html]] SMD soldering with simple means
-  * [[http://www.reichelt.de]] There are almost all components there+  * [[http://www.reichelt.de]] Almost all components are from there
   * [[http://shop.lipopower.de/1050-mAh-Einzelzelle-1C-30mm]] The LiPo of my choice   * [[http://shop.lipopower.de/1050-mAh-Einzelzelle-1C-30mm]] The LiPo of my choice
   * [[http://shop.lipopower.de/PCB-2-A-1-Zelle-Lipo-LiFePO-137]] The LiPO protection PCB   * [[http://shop.lipopower.de/PCB-2-A-1-Zelle-Lipo-LiFePO-137]] The LiPO protection PCB
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 ==== Donate ==== ==== Donate ====
  
-If you line my articles feel to donate a cappuccino or so...+If you like my articles feel to donate a cappuccino or so...
  
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