如何用LM358做可调方波发生器

因为需要,想用LM358做一个28-400Hz可调的,占空比为50%的方波发生器,网上找了点资料,搭了一下最后只调出一个50Hz的方波(是不是市电干扰的缘故),想请教大家一下这个电路用LM358可行吗?有没有更好的办法?(原理图上是用双电源,我用单电源可行吗?)
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另外有刚刚找了两张图,还没实验过,不知道可行否
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先谢大家了!