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Simple AC circuit simulation

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cjohnson 3 years ago

EDIT: Wow, theta was set to 1. Sorry everyone, if you see a degrading AC power supply make sure to check your Theta value. I threw this in to Tips & Skill, because I'm hoping to learn something here. I've used LTSpice before, but it's been a few years. Setting up a simple AC -> logic level power detection circuit for 24-48VAC. The circuit we are already using works, but I'm going back to simulation to see if I can improve the noise we currently have in the circuit. Anyways, when I setup this simple analysis ![image.png](//image.easyeda.com/pullimage/MdSfT9w60OmPWVSUKq1MDqNOeejRStMfZ0VZoYsh.png) I get an AC power supply that degrades over time, and I know I've got to be missing something simple but I just can't figure it out. ![image.png](//image.easyeda.com/pullimage/0mBgLrZ59J1B5iS4CiHpQedfvq04T9HtFP4h6T3o.png) TIA

Chrome 83.0.4103.97 Windows 10 EasyEDA 6.3.53

Comments

andyfierman 3 years ago

There are lots of examples of how to [configure voltage and current sources](https://docs.google.com/document/u/1/d/1OWZVVFRAe_2NW3WratpkA_SGuHa5AcRow5ZRfvcoVTU/pub#h.bq0i7caw31bh) for Transient and AC Analyses in the Simulation Tutorial (3) in (2) in: [https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a](https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a) :)

Chrome 80.0.3987.163 Ubuntu EasyEDA 6.3.53

andyfierman 3 years ago

Note that for an AC Analysis you have to explicitly append `AC 1 0` (or whatever is appropriate for your sim) to the relevant voltage or current source in your sim. So for example if you want to do a Bode plot of output vs. signal input you'd append `AC 1 0`to the input signal source and just probe the output. If you wanted to do a Bode plot of power supply ripple rejection, append `AC 1 0`to the power supply source and just probe the output. If you want to do a Bode plot of reverse signal transfer you'd append `AC 1 0`to a suitable source connected to the output and then probe the input.

Chrome 80.0.3987.163 Ubuntu EasyEDA 6.3.53

cjohnson 3 years ago

Thanks @andyfierman I appreciate the extra info here.

Chrome 83.0.4103.97 Windows 10 EasyEDA 6.3.53

你现在访问的是EasyEDA海外版，使用建立访问速度更快的国内版 https://lceda.cn(需要重新注册)
如果需要转移工程请在个人中心 - 工程 - 工程高级设置 - 下载工程，下载后在https://lceda.cn/editor 打开保存即可。
有问题联系QQ 3001956291 不再提醒

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