miracleblue

I have a couple questions regarding parameter definitions. I would really appreciate the help. 1. In most of the transistor, I've noticed that most of them have the term "Junction to Free-Air Thermal Resistance" and "Junction to Case Thermal Resistance". I am confused about this matter, so I just want to ask, what is the definition of those terminologies. 2. Ripple!!!! All this while, I thought of ripple as a small oscillation due to a filter. Am I right? Thanks in advance.

First of all, thanks for all the replies. I really appreciate it. Couple of comments: I do not have all these materials. Perhaps in making the real piece PCB down in the lab, they may have it. Forgive me if I ask this, but what do you mean by circuit design stage? It is true that Orcad Capture can't make any PCB layout. It can only give you the schematics of it. However, there's Allegro/Layout that can just take the netlist file of the schematics. The thing is, I don't know how to do that yet. I think I need to go to the Orcad forums and ask there.

I am learning how to make a PCB board using OrCad Capture CIS version 10.1. I've created the whole schematics for the circuit. The question is, what are the steps that is needed to make actually come up with PCB board layout? I will be greatful if someone can help me. Thanks in advance.

@ reverse: No, I don't know that a transformer can do that. Thanks for sharing the knowledge. I will try it when I have the time and resource. Kinda low on budget for this project alone. @ YT2095: I'm sorry to ask this, but I have never came across the term "Mark-Space ratio" before. If you don't mind, can you point me to some useful links that explains that terminology. It seems pretty sophisticated. An update on the circuit that I've tested, if the filtering capacitance change from 1 uF to 0.1 uF, the ripple output is really showing on the scope, which is expected. I've tried to use different values of resistors as well, but I can't find an obvious pattern.

RICHARDBATTY, thank you for responding. Here's the desired conversion factor: sending 2 kHz ---> corresponds to 5 V Example conversion: 810 Hz ---> would correspond to 2.025 V (if my calculation is not wrong) Well, not to worry about the ripple. I am going to use the same one as given in the data sheet as it gives a pretty stable output. Under oscilloscope, it almost resembles a straight line. However, if you think that the filtering capacitor should change, try to make it within 10% error, including ripple. That is already pretty good. Let me know if it is not possible.

Hello everyone, I am using LM331 Precision Voltage-to-Frequency Converters. In the data sheet, there's an application for the purpose of Frequency-to-Voltage Converters. Below is the link to the data sheet: LM331 Data Sheet Using a frequency modulated laser to send information, on the receiving end, there will be a photo-electronic sensor, a photo-transistor, LF14F1. I've tested the modulation scheme on both sending and receiving ends of transmission. They works perfectly. The square waves that is sent through the laser gets received as the original signal with all its properties (Vpeak-to-peak, frequency). However, I would like to convert the frequency on the receiving end to be in terms of voltage. Thus, adding a LM331 can make it. According to the data sheet, it can take any input as high as 10 kHz FULL-SCALE, and outputs 10 V FULL-SCALE, under 15V power supply. I've tested this one, and it works like magic. Please look at Figure 1 However, I need to make it to work for a minimum of 1 Hz - 2 kHz at max at the input and outputs to be anywhere between 0-5 V, since I am using a 5-V regulated power supply. There's a formula to determine the Vout at the bottom of page 8 of the data sheet or to the side of Figure 1. I'm new to engineering design, and I just wanted to know, which of the Resistors/Capacitors should I change? My guess is to get to lower frequency, I need to tweak the Rt and Ct values, and to change the output voltage, I should tweak RL and Rs. Please help me to confirm this. I would appreciate it if anyone can help me. Thanks in advance.