UT61E digital multimeter schematics and integrated circuit datasheet

ES51922 application circuit for ES51922 datasheet. In UT61E 1some features of ES51922 are not used and can be enabled by simple hardware diy: 112 APOSEL I Idle time selection for auto power off feature. 58 SLEEP O Sleep mode indicator, asserts low in SLEEP mode. 105 BKOUT O If BKLIT function is enabled, this pin will change from –3V to +3V For 60 sec, once press BKLIT pin again within 60 sec, this pin will Change back to –3V 102 BKLIT I Back light function. Pulse low to set BKOUT…

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Adjusting and calibrating Hameg HM-605 channel gain

Yesterday I have noticed that voltage or gain of channel 1 in my scope is a little bit off ( noticed that by analyzing one circuit on same output with dual signal ). I have Hameg HM-605 service manual (you can download it at the bottom) and I found there instruction of adjusting channel gain. Basically you just provide square wave signal ( I used scopes calibration output ) and adjust corresponding pot. Its an easy fix as you can see in a video below. https://www.youtube.com/watch?v=ZWKAdgnhqh8 Download HAMEG HM-605 oscilloscope…

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Getting cheap oscilloscope on ebay

As casual electronics tinkerer I have always wanted to add an oscilloscope to my tools collection but never did so. There are many reasons why, for example, oscilloscopes are expensive and you don't want to spend a huge amounts of money on thing that will be used just occasionally and basically is a "toy", or, for example,  I have never owned one and there are gazillions of them and I was not sure which one or with what specs should I get. You can have modern digital ones, older analog,…

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Repairing HAMEG HM-605 oscilloscope trigger problem

Bought used HAMEG HM605 oscilloscope with trigger problem. Tested it with sine wave and yes, cannot trigger it nor with automatic trigger neither manually. Decided to resolder all contacts near the trigger switch. Luckily it was easy accessible, just had to remove cover. After resolder next test revealed that sometimes trigger works, and sometimes not. Just a slight touch (no pressing) on external trigger button seems to be cause. So I resoldered all the contacts of ext trigger switch and some around and triggering started working as intended. Fixed. https://www.youtube.com/watch?v=Gkyj85Is7uw

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Signal Differentiation and Integration

Good explanation about Differentiation "The output wave of a DIFFERENTIATOR CIRCUIT is ideally a graph of the rate of change of the voltage at its input." Fig.8.4.1 The Differentiator Circuit Fig 8.4.2 Differentiation. -------------------------------------------------------------------------------------------- And Integration "The shape of the input wave of an integrator circuit in this case will be a graph of the rate of change of the output wave " "The low pass filter circuit is therefore called an integrator only when: a. The input wave is a square wave. b. The periodic time(T) of the input wave is…

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