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Re: Analog ESR meter design
marcdima
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Re: Analog ESR meter design
^ i think this is the meter :
http://pro-radio.ru/measure/10248/
The links in the text point to an older and similar through hole version with source code and everything available.Comment
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Most analog meters are actually current driven - a current is needed to deflect the pointer full scale. They can be lots of different values. There are ones that can take several amperes to swing the pointer as they have internal shunts.
On the other hand there are many that are rated in microamps for the intent that they draw as little power as possible from the devices under test. Some are 1mA, 500µA, 200µA, 100µA, and the ubiquitous 50µA frequently used in analog VOMs. There are even 20, 25, 30 µA and even down to 10µA. Been collecting a bunch of different ratings and... -
Hi
I want to change the scale of an analog meter, to monitor the charge of an li-ion single cell, so the needle at the end would point 4.2 volts and the 0 on the meter would point 2.5 volts or so, i tried to add diodes or a zener in series with the meter but the changes of the ambient temperature also changes the voltage value on the meter
I wonder how i can accomplish this so the meter would be precise at any temperature ?
Thnaks -
Hi.
Quick question.
I have a laptop that is completely dead. I opened it up and it looks like the current sense resistor is blown. However, because it's blown, the value printed on the top has disintegrated and there is no schematic available for this particular laptop (Dynabook Portege) so I'm not sure what to replace it with. -
Hi
I am trying to repair an ancient Dell 2209WA Monitor which suddenly shut off with a pop sound. On investigation found that one of the fusible resistors had blown. Further investigation identified multiple components as faulty because of which the fusible resistor blew. Please refer the attached circuit diagram showing the components that were found to be damaged.
1. FR950 - blown fusible resistor - 0.2 Ohm 1W
2. Q950 - shorted Q950 MOSFET - 650V 10A N Channel Mosfet
3. R835 - Blown Resistor - 20KOhm SMD resistor
4. D930 - Shorted Schottkey Diode... -
Hi to all forum members,
Got this faulty 350 watt atx psu dirt cheap from a local online seller as i am keen to use it as a learning tool to repair faulty power supply.
The faulty part is quite obvious from the burn area near the 16pin KA7500 BD pwm. The fuse is still intact with good continuity.
Upon power on ac, there is 5vdc standby power on cathode of diode D14 and about 10vdc on cathode of diode D13.(This should be the aux power to generate the 12v and 5v rail.)
Initially i replace the two burned resistors near my marked red arrow to 200 ohm resistor...
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