All right, since my name has been mentioned, I'll make one more post in this thread. No doubt if Simon thinks it's inappropriate he'll delete it.
Just for the record I tried to avoid all the negative statements about the circuit, but it got so intense and extended that I had to counter it. I don't care, but the problem is that others, who don't know about design, who read this thread will think that the comments you have been making are relevant and that the circuit is no good. This has happened quite a few times on other threads.
Another thing to remember is it is not your prerogative to tell members how to design or demand that they do this or that. As far as I know you are just a member, like everyone else. For example, if I want to use split supplies- and I have good reason for doing so- I will. I don't need your approval. You will notice that I have made no derogative personal remarks about you, just about your posts.
This is all a great shame, and it is an even bigger shame that Soldar got mixed up in all this, because I know that you are interested in electronic design, and you have some great ideas- I have said so, but it is the nature of your posts and the fact that you will not see reason in many cases, that is the problem.
If you reread this thread with a non-defensive mindset, you'll find that Soldar and I said that your circuit adequately meets the original poster's needs, so long as their requirements regarding duty cycle are not stringent, which we both assumed to be the case.
Please accept that any circuits you post will often receive some critique, both valid and invalid, which is not against the rules of this forum, so long as it's conducted in a polite and respectful manner, as has been the case here. Responding to invalid criticism is perfectly fine too, again, as long as it's done in a polite and respectful manner. Responding in a defensive and rude manner is frowned upon here and going by the moderator's response, appears to be against the rules.
Bear in mind that not everyone is an expert. Someone may think something doesn't look right, when in reality it's fine. Quite often a design will meet the requirements, but some will get carried away suggesting improvements, which aren't absolutely necessary. This is good because it might raise points which others may not be aware of. For example in this case, I got carried away striving for perfect 50% duty cycle, which I agree is not needed here and in the process raised the point about the asymmetry of the 7555's output stage. Perhaps you were already aware of this, maybe not, but in either case, I'm glad I raised the issue, as there will certainly be some people reading this thread who are unaware of it. I also discovered myself how poor the accuracy of the 7555 is when breadboarding it.
The 555 timer is often seen as the first IC of choice for many applications, especially by newcomers. Unfortunately, in reality it very rarely is the best solution to a problem. Isn't very beginner friendly, especially the old TTL version, with all its quirks such as drawing huge current surges, therefore requiring very good decoupling. Again, I'm not telling you not to use the 555, just that it has its shortcomings, which I'm sure you're already aware of. In this case the high output current capability is attractive, as it can be made to source/sink the full output current, if necessary.
No one is telling you how to design a circuit or making any demands. You cite my comment about split supply rails, but I was merely suggesting an alternative approach, not mandating anything. There are always multiple ways to solve a problem. You may post a design which solves the original poster's problem, but it's highly unlikely that it will be the only way of doing it and it may not be the most efficient or best way.
It's a great shame an interesting technical discussion has degenerated into personal attacks and apologise for my part in it. If you feel any comments or critique of your circuits is conducted in a rude and disrespectful manner please report it to the moderator. You might also want to consider sending them a private message, before doing this, in the hope it can be resolved in a peaceful manner, rather than raising it on the public forum.