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Yes, you are right. And I am thinking to start with the PICAXE because easier to handle. Maybe, after some practice I become addict of PICAXEs ;D. Frankly, now I don't have spare time. This circuit is the electronic module of a project which I will use personally for commercial purpose. I am also considering to use the industrial timers. What do you thing, which choice would be more heavy duty type. The ready-made version based on induction heater, is very expensive......$25,000+ As for the relays, I plan to install them separately, not on the board.

My objective is to insert a PVC tube in a the (cold) mold. The heater should heat the mold to an ideal temperature to melt the tip of the PVC tube inside the mold (for a few seconds) and then the heater must switch off and the mold must be cooled down immediately by circulating water through the outer sleeve of the mold. The mold is made with steel for experiment only. I inserted the tail of the mold in a 45w soldering iron as shown in the picture. My test was successful. I plan to build a set-up in which I can use molds of various working sizes. I mean, the outer dimensions of the mold will remain the same only the hole diameters would vary to match various sizes of PVC tubes. The actual molds will be coated with chrome or nickle. And, if required, I can change the material of the mold to aluminum, copper or brass for better conductivity. The mold would be installed inside a cooling sleeve, which cover only the body of the mold (excluding the tail). After testing the trial mold on a soldering iron, I planned to use a soldering gun which heats the tip more quickly. Here is my proposed idea to quickly heat-up the mold. The transformer's secondary winding is 2/3 turns of 4 SWG solid copper wire to give 2-4volts but high amperes like 400 - 500A. The rest circuit is self-explanatory. The pictures of the mold is also attached to give you the idea of the size of the mold. Lastly, I want to use 4 such heaters connected parallel and work at the same time. Questions: What kind of cables/wires should I use to connect the Transformer-Relay-Heater ? What should be the amperage of the relay to switch on the Transformer?

Hmm, your advice is good. But, in my area all those components are very cheap. And I am pretty sure to complete the PCB for about $20-25 only, including the relays!!! I had enjoyed programming a lot from 1988-2002. I understand that computer, electronics etc. are all to get maximum benefit with lesser effort/cost. But, I like working with basic components. PIC or PICAXEs are just like computer programming, I cannot enjoy the electronics with them. Anyway, that's my thinking. Maybe I am wrong. Thanks for your help/suggestions.

Thanks for responding. Yes, NE556 is a better option. In that case it would be 556+555+556. Any more suggestions to improve the circuit, keeping in view that the relays are to switch on 220v devices.

Hi I am working on a project which needs 5 timers. First, please see the flow chart. Next, the time graph for better understanding my requirement. Finally, the proposed schematic. I shall appreciate, valued suggestions to finalize my project. By the way, being a hobbyist, I have limited knowledge of electronics. Thanks.