ideas of delabs

Analog Design to Handheld Computing. Ergonomics and GUI Usability. 30+ years in Electronic Product Design. 80s EE Design Notes, 90s EE Web Logs. - delabs Technologies

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Friday, May 03, 2019

Engineering Poetry and Heuristics

Knowledge comes in Handy at every part of your Life. Entertainment should be Edutainment. Here is a collection of comments and blurbs i wrote around 2012 - delabs

Verify Again and Again

After doing something, Verify, ask a friend to crosscheck, verify again.

Engineering Poetry and Heuristics

Wait there is more ...

Then ask somebody who does not like you so much, to check or test it and offer critical comments.

delabs design service - Circuit and product design

Differential Amplifier - Op-Amp Designs

A very simple one op-amp diff amp. This amplifies the difference between two inputs Vp and Vn the low impedance of this configuration is a drawback, but can be used in analog computing. Optimum VCC VDD can be +12/-12. AC signals common to Vp and Vn are canceled by this configuration.

Differential Amplifier - Op-Amp Circuits

Differential Amplifier - Op-Amp Designs

Use a capacitor like 10nF plastic from pin 2 to 3 or across R2 to make circuit stable. For AC applications use LF351 TLO71 as they have good slew rate and also are FET inputs. For AC applications use a capacitor (1uF) in series with Ri to block DC Components.

Buffer Unity Gain Amp - Op-Amp Designs

If output impedance of a point is a high value then connecting another circuit at that point will load it, resulting in malfunction or error. Buffers are used as interface between circuits.

Low impedance of an output means it can source/sink lot of current, when you need 2 opamps use LF353 or TL072 which are dual opamps.

Buffer Unity Gain Amp - dapj Tech Widgets

Buffer Unity Gain Amp - Op-Amp Designs

A non-inv FET input is the best buffer, for inverting buffer use high R values. Using very high R values like 2.2M or higher requires a glass epoxy PCB and guard rings around pin 2, 3 to prevent leakage currents on the PCB reaching the PINs.

Also moisture and dust has to be prevented by using RTV coating or Varnish. Use 78L05 and 79L05 for the dual supply required by this circuit.

Inverting Amp   -   Vout = -1 * Vin

Non-Inverting Amp   -   Vout = Vin

Vary the Millivolt Source by just hovering your Mouse pointer over the Two Buttons (Increment and Decrement). If you leave the mouse pointer on a button, the variation will pick up speed. Set a Value of your choice, positive or negative, you can set from -199.9mV to +199.9mV. Note the Output values on both the DVMs on the right (digital Volt Meter) in a Table. Repeat this for at-least 7 readings of both polarities. Jot the Formula below in your book and relate it to your table.