electronically controlled variable speed pulse generator?

[mbarazeen]

ok, i got whre you struggle, so its better you continue with what you have done so far, make a square wave oscillator and use devider to change the speed. say for example when you reverse pass the pulse train via a 4017 counter that can devdie the pulse by 2-10 as you chose.

 

[mbarazeen]

attached is how you can make a devider using 4017 that can be varied by simple logic input.

Edit: made a mistake in the wave form, corrected..

 

[crosslakeguy]

That makes sense, to use a devider. I am wondering what type of circuit you had in mind To control the number of pulses, for distance. that is how the cnc program operates. Is there some way of doing this without a micro-controler?

 

[mbarazeen]

Is there some way of doing this without a micro-controler?

for sure it can be done using counters and basic gates. but the flexibility of programming (in another word settings) can only be provided up to an extent.

so far i did two interesting tasks using this idea, both i tested to work

1) a copier to a memory chip it will read with serial communication and write to another identical memory and the size of the memory can be selected. if any error occurs it will re-do the cycle automatically, finally hold the operation when all sectors are copied. (only for a particular series of EEPROM)

2) a 12x12 multiplication quiz game, select two numbers 1-12 and multiply them and get the answer displayed.

these all fictions based on counters and logic gates. no processor at all.

so i am very certain, your task is bit easier than those above and can be done without a processor.

But if you learn to use a processor and memory you can run different set of instructions that will give you a lot of flexibility. i have the idea but have not tried yet. it need programming skill too.

but if your requirement is to run only a fixed setup / operation then this method also can be worth.

 

[Roff]

Crosslakeguy, I designed a circuit which turned out to be essentially identical to alec_t's circuit, except for the resistor and pot values. The simulation works well.

 

[crosslakeguy]

Is the circuit adjustable without a potentiometer. how is It adjustable? I assume the 4066 is a series of values........? I kind of understand , but a explanation would help me greatly...?

 

[Roff]

Is the circuit adjustable without a potentiometer. how is It adjustable? I assume the 4066 is a series of values........? I kind of understand , but a explanation would help me greatly...?

Look at the **broken link removed**. There are two pots, one for the high range and one for the low range. The 4066s are digitally controlled switches. U2a and U2c switch in one or the other of the two pots. U2b along with R1 act as an inverter, so that when U2a is on, U2c is off, and vice-versa.

Attached is my design, which, as I said, turned out the same as Alec's except for values.
You will get close to 50% duty cycle with an LM555 or NE555. With a CMOS 555, it will theoretically be exactly 50%.

 

[mbarazeen]

i have attached an example how you can provide a set of pulses with exact count, here 4060 ripple counters output has been selected so that after 2^5 pulses (32 pulses) the particular output will go high and hold the pulse output. when it is integrated with other circuits it will allow 32 pulses and stops.

 

[crosslakeguy]

Hmmmm......... interesting.........I have yet not looked at the IC, but how is the duration controled? ....thanks much for everyones help, I have looked through pastposts. and to simplify, Only low speed needs to be varariable then switch to a preset frequency for high. Please explain 2/\5 I don't have a key for that? I think I understand, but I have not formal school, so am not familiar ?

 

[mbarazeen]

Hmmmm......... interesting.........I have yet not looked at the IC, but how is the duration controled? ....thanks much for everyones help, I have looked through past posts. and to simplify, Only low speed needs to be varariable then switch to a preset frequency for high.....

duration can be controlled at the input as discussed previously, by deviding or by controlling at oscillator end....

 

[btsutton]

Digital pot circuit with manual up/down.

I think you had mentioned using a digital pot back in one of your posts. I ran across this and it looked like it would work for your app.

**broken link removed**

 

[crosslakeguy]

Just wanted to thank you guys for your help and input, I won't get a chance to put something together for while, I hope some other people run across this information and also find it helpfull