apummer945

's profile
image
engineer

Biography has not been added


apummer945

's contributions
  • 08.04.2017
  • Build your own oscilloscope probes for power measurements (part 1)
  • Short the newly created probe's input to it's own ground, and touch any ground with that shorted input probe to any ground of a working -- under power -- power supply, despite the probe input is shorted you will see signal on the scope's screen...The scope's input ground is not on the same "noise potential" as the power-supply's ground, therefore there will be a "noise current" between the two grounds, which will cause a noise voltage between the two end of the probe's cable shield. If you open the short at the end of the probe and using the probe to see voltage wave-forms in the power-supply, that noise voltage will add to the wave form what you observing in the circuit. You could eliminate that problem, if you are using a differential probe, or if you modify your newly created probe with common mode suppression, by using large ferrite sleeves or rings, just pull the probes cable a few times trough a sleeve, more is better. You could test the result by shorting the probe input again and connecting it to the power-supply's ground, you should see much lower or almost nothing on the srceen.
  • 08.15.2016
  • Monolithic JFETs are alive and well
  • these links are broken: here's an app note Bob Cordell did for us that has some of those for the N-Channel counterpart: http://linearsystems.com/assets/media/application_notes/LSK489_Application_Note.pdf. Another one by Ron Quan using the LSK489 for sensor applications: http://linearsystems.com/assets/media/application_notes/Guide_Use_FETS_Sensor_Applications.pdf
  • 04.04.2017
  • Slippin' and a slidin'
  • yes that resistor will prevent the input from floating, but depend on the ratio of the resistor value and the pot-meter value it will modify division ratio and it will constitute one additional load to the signal source. Potentio-meters with sliding wipers were used in old radios as volume control, they wear our caused noise by turning, a drop of thick silicon oil, which sealed the pot-meter made a wonder, the old potentio-meter worked fine again
  • 12.05.2008
  • Solar-array controller needs no multiplier to maximize power
  • Since EDN is not available in printed form any more, I usually save the article of interest in the .pdf file form and read it later. Sometimes I get a surprise; the figures of the article are not available any more... now the whole article is useless! Would be possible to -- at the editor's office -- put the figures into the same .pdf file which contains the text?
  • 03.01.2007
  • Low-cost current monitor tracks high dc currents
  • the link link of the reference Improved ... EDN Jan 19 is broken the current to frequency converter via core saturation suffers from dual non linearity: a tank circuit's frequency is changing with the square root of the inductance, and the saturation curve is also not linear, additionally also temperature dependent, but the idea could be developed further to get good result
  • 09.01.2006
  • Is engineering a profession?
  • actually engineering is a call, and if somebody does not take it that way he or she is not an engineer
  • 08.15.2016
  • Monolithic JFETs are alive and well
  • It is definitely a problem if engineers do not understand basic circuit design, I see that on daily basis and making a very good living that...