| Electronics > Beginners |
| 555 LT Spice issues (trying to produce ~7kHz ~sine wave) |
| (1/3) > >> |
| jpyeron:
I was simulating a circuit (spice model: 7khz-carrier-wave.asc) and I was surprised that my calculated RC values were significantly off. I expected to use a R2 resistance of 10307 ohms, but had to use 9857.6 ohms. After a bunch of googling I ran across alternate (1.38) [1] calculations for a 555 when calculating the period which is what LT spice seems to be using. The datasheet is using 1.44 [2]. I tried to edit the builtin model and got a restriction error - . I tried to import a TI spice model [3] and got this error - . Thoughts? 1: http://www.embeddedcomponents.com/blogs/2008/03/simulating-the-555-ic-with-ltspice/ 2: http://www.ti.com/lit/ds/symlink/ne555.pdf 3: http://www.ti.com/product/TLC555/toolssoftware |
| jpyeron:
The final circuit will be tuned at assembly. At the same time, still frustrated by my building blocks 5% out from the datasheet. |
| jpyeron:
How do I fix this in LT Spice? |
| iMo:
The DS is using 0.69 for a different circuit, imho. |
| jpyeron:
I ran the simulation with the DS circuit first. I had the same 1.44 vs 1.38 issue there. The LT Spice ideal 555 is using the 1.38 in its model - which is not adjustable. I downloaded the TI spice model, but the param error is way out of my spice knowledge. I have not used spice sine the late 90s. |
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