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  1. 2

    Ramping signals with op amps?

    Hello, I have tried all day to make sense of this... calculation after calculation and I really don't get it. I need some clear and concise help !!! :( Please refer to the image attached. I would like to be able to build and calculate (for my personal learning) an op amp that takes a 3 to...
  2. 2

    Ramping voltage to current converter?

    hello, I have a ramping voltage signal of 0.4VDC to 1VDC commingbout of an op amp. I need that signal to control linearly an IR led’s current that can vary from 0-1A. Therefore I want to convert a 0,4VDC-1VDC to 0A -1A Therefore the output of my op amp needs to go to a device that can drive...
  3. 2

    PCB layout software?

    Hello, I was thinking to try and do my own PCB layouts myself And then generate the gerber files so I can Give them to my PCB manufacturer. But I never used such a software and I would like to ask this forum which one I should use? It should allow me to design layouts from the smallest to...
  4. 2

    RF balancing (50 ohm traces, baluns etc...)

    Hi, I am using an RF MCU chip which comprises an RF transceiver and an MCU. The company that sells this RF chip provides a recommended RF circuit schematic which shows how the device should be wired. The schematic shows the RF MCU along with some external coils baluns and capacitors. I also...
  5. 2

    25V vs 35V capacitor?

    hello I am using the following power supply along with the external devices shown in the EMC recommended circuit section. The problem is the recommended C2 capacitor’s diameter is too large. It’s 8 mm but I would need something like 6 mm. In reference to power supply part# : PBO-5-S3.3, under...
  6. 2

    Measuring the current used in a power supply?

    hello, I have a power supply converter that converts 120VAC to 3.3VDC at 1A. I would like to know (without measuring with an ammeter) when I am drawing 800 milliampères or more. When 800+ milliampères are used, I want to light up a led to indicate that the power supply has attained 80% of its...
  7. 2

    The curve of the sun?

    Hello, In reference to the following link: http://www.physicalgeography.net/fundamentals/6i.html In reference to the graph on page 2 of 4 (Fig. 6i-2). What are they trying to tell me? If we look at the 50 degrees North line (The red one), It seems that approximately in mid June, the maximum...
  8. 2

    Level signal compatibility?

    Hello, I have an output from a quad 3 state buffer chip 74LS126 (Which operates at 5.0Vdc and its output will most likely be 5.0VDC when high) and this output needs to be fed into an input of a PIC32 MCU which its maximum input voltage tolerance is approx. 3.6VDC. Assuming the MCU takes in...
  9. 2

    Led flikers?

    Hello, I am designing a small board where it requires several power supplies. they are 3.3VDC, 5VDC and later perhaps 12VDC. In this board, I am trying to design a small circuit which detects if any of these voltages are missing on the board. If all the voltages are available a green led will...
  10. 2

    looking for a 10 bit transceiver with latches?

    Hello, I have found this part at: http://www.ti.com/lit/ds/sccs035a/sccs035a.pdf which is a unidirectional 10 bit latch with 3 state outputs employing two enables of which I require in my design. I was wondering though, is there any parts out there that have the same thing but...
  11. 2

    Malloc and it's use with MCUs

    Hello everyone, I have a project which needs to work in real time and can't afford to hang or undergo any access violation issues during its execution. I typically use malloc/free extensively!!! Then, I stumbled on the first few paragraphs of the following article: (see around the middle...
  12. 2

    Definitions for op amps?

    Hello, I have done some op amp calculations, but I am a little confused about equation definitions. In reference to attachment, can someone please confirm the following definitions in respect to gains: Inverting configuration: G1 = -rf/ra Non-Inverting configuration: G1 = -rf/ra G2=...
  13. 2

    What is the best CMRR definition:

    Hello, I have seen many definitions in many articles throughout the Internet... here are some of the definitions I found: and so on.... But my question is, for example, for a given differential op amp circuit, if we have a CMMR of: CMRR = Ad./Acm CMRR = 2/1 Can we say that in this case...
  14. 2

    What is the curent of a unity gain differential op amp?

    Hello, In the following op amp configuration, can someone explain how much current is going through ra and rf? If the ra voltage drop is 0 Vdc, how could there be current going through ra?? :confused: thanks!
  15. 2

    Op amp configuration with 1 resistor ?

    Hello, I understand how to evaluate several op amp circuits now namely, non-inv, Inv, diff etc... , but today I have come across an untypical op amp configuration with only the rf resistor? Please view attachment. At first I thought it looked simple but I was wrong. My question is, how is one...
  16. 2

    Quick question about equal input voltages for op amp?

    Hello, If we have an op amp (LM324) with rail voltages of +/- 15Vdc, and we short both inputs to +5Vdc, is it normal that we get 13.7Vdc as the output??? I read everywhere that if both inputs are equal, the output should be 0 Vdc !!!! But here on my test bench I get +13.7Vdc ...
  17. 2

    Quick current direction for op amp question?

    Hello, In reference to the attachment below, which way is the current going. Please choose from A or B. Thank you 24v
  18. 2

    Op amp calculations for ramps!

    Hello, In attachment below, I have an op amp which takes in 4 vdc and outputs 5vdc. The circuit has been calculated by using the non-inv op amp formula: vo = [1 + rf/ri] v2 5 = [1 + 15k/10k] x 2 However, if I ramp up the input from 4vdc to 6 vdc, I measure 7.5vdc at the output when the input...
  19. 2

    Quick op amp question?

    Hello, I have very little experience with op amps. I know how to calculate the voltage outputs of a differential, non inverter and inverter op amp circuits. But can someone explain to me in a simple sentence as to why it is important to be able to calculate the common mode gain and the...
  20. 2

    How does gain apply in diff op amp?

    Hello, Intuitive deductions in reference to attachment: 1) Initial op amp assumption: Output = 0V Va will sense: va = v1(Ri/Rf+Ri) = 2(10K/30K) = 0.6VDC.... Therefore: 2-0.6 = aprox 1.3VDC Vb will sense: vb = v2(R2/R1+R2) = 5(1.5K/5K) = 1.5VDC Therefore, since the Non inverting input >...
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