Done that, but now it doesn't move for the first part of the cycle, then starts up to go the other way. Is that because I have the switches wired up NC?

 

The first part is when RLY1 is operated. S1 must be closed (not pressed). The motor movement should then continue until S1 is pressed which should stop the motor.

The '555 switches and the motor moves in the opposite direction until S2 is pressed. That movement should also release S1 read y for the next cycle.

Can you make sure that S1 and S2 are correctly for these motor movements.

 

Albert's suggestion likely doesn't work because the 555 output high voltage is about 1.5V or so below Vcc and thus Q2 never turns off.
To avoid the problem he noted, connect a 1k resistor between Vcc and Q1's collector in your original circuit (with R2=20k).
That will provide power to the circuit even when S1 is open.

 

I think that did it! Moved round, hit the switch, turned off then started up when it timed out! Once I finalise the mounting framework for it all I can try it with both switches but I'm confident it'll perform.

Thank you SO much all, I was starting to despair about the project but you've sorted it! Was also a bit worried you'd think I was trolling, as who could be so clueless? Thanks again - I'll try to update the schematic to represent the final build, so others can benefit.

 

....................
Thank you SO much all, I was starting to despair about the project but you've sorted it! Was also a bit worried you'd think I was trolling, as who could be so clueless? Thanks again - ...............

Glad you finally got it all to work.
It seems apparent that no-one ever built your original circuit since it can't work as drawn.

Nah, nobody thought you were a troll.
You aren't even good enough to be an apprentice troll.

 

Hello! I promise I've searched and tried to work this out but my background is scale modelling, so I'm really just lost here.

My friend asked if I could figure out a way to avoid spending £3k on a vacuum casting machine. It's two cups, one above the other, each holding a different half of the epoxy resin mix. Top cup tips into the bottom one, there's a mixer going, then the bottom cup tips into a mould. All in a vaccum to avoid air bubbles.

I managed to sort out 555 timer circuits to time the operations, and needed a solution to tip the cups then right them again. I thought the rotation of a ~30rpm motor would be good, with a pause to empty, then back upright.

Google gifted me with SgtWookie's circuit here:

http://forum.allaboutcircuits.com/t...ggled-by-555-timer-with-limit-switches.61897/

So brandishing the soldering iron, I managed to cobble it together on some perfboard.

I added the decoupling capacitors he recommends as an addition to his design, and I have replaced R3 and R4 with 56.1k resistors to get near the time I need and adjust them from there. I am powering the whole shebang from a PC PSU.

Circuit schematics are a bit of a mystery to me, so I made the following assumptions - the relays both wanted the NC connecting to ground, and the switches had no polarity and needed connecting by the COM and NC tabs, with nothing on NO.

Powering up, the motor rotates counter-clockwise, then times out, but stays still until timing out again, at which time it resumes going counterclockwise. I can hear what I assume are the relays clicking.

So, I made it again, as I must have broken something, but with the same results.

Sadly, I have no idea what parts are meant to reverse the polarity to get the motor to go the other way, or if that's even the problem. Maybe I am a clumsy solderer and have broken the relays or something.

Could anyone suggest what may be wrong with the circuit, or more likely what rookie error I've commited? Thanks in advance!

Luke

Hello! I promise I've searched and tried to work this out but my background is scale modelling, so I'm really just lost here.

My friend asked if I could figure out a way to avoid spending £3k on a vacuum casting machine. It's two cups, one above the other, each holding a different half of the epoxy resin mix. Top cup tips into the bottom one, there's a mixer going, then the bottom cup tips into a mould. All in a vaccum to avoid air bubbles.

I managed to sort out 555 timer circuits to time the operations, and needed a solution to tip the cups then right them again. I thought the rotation of a ~30rpm motor would be good, with a pause to empty, then back upright.

Google gifted me with SgtWookie's circuit here:

http://forum.allaboutcircuits.com/t...ggled-by-555-timer-with-limit-switches.61897/

So brandishing the soldering iron, I managed to cobble it together on some perfboard.

I added the decoupling capacitors he recommends as an addition to his design, and I have replaced R3 and R4 with 56.1k resistors to get near the time I need and adjust them from there. I am powering the whole shebang from a PC PSU.

Circuit schematics are a bit of a mystery to me, so I made the following assumptions - the relays both wanted the NC connecting to ground, and the switches had no polarity and needed connecting by the COM and NC tabs, with nothing on NO.

Powering up, the motor rotates counter-clockwise, then times out, but stays still until timing out again, at which time it resumes going counterclockwise. I can hear what I assume are the relays clicking.

So, I made it again, as I must have broken something, but with the same results.

Sadly, I have no idea what parts are meant to reverse the polarity to get the motor to go the other way, or if that's even the problem. Maybe I am a clumsy solderer and have broken the relays or something.

Could anyone suggest what may be wrong with the circuit, or more likely what rookie error I've commited? Thanks in advance!

Luke

 

Hello! I promise I've searched and tried to work this out but my background is scale modelling, so I'm really just lost here.

My friend asked if I could figure out a way to avoid spending £3k on a vacuum casting machine. It's two cups, one above the other, each holding a different half of the epoxy resin mix. Top cup tips into the bottom one, there's a mixer going, then the bottom cup tips into a mould. All in a vaccum to avoid air bubbles.

I managed to sort out 555 timer circuits to time the operations, and needed a solution to tip the cups then right them again. I thought the rotation of a ~30rpm motor would be good, with a pause to empty, then back upright.

Google gifted me with SgtWookie's circuit here:

http://forum.allaboutcircuits.com/t...ggled-by-555-timer-with-limit-switches.61897/

So brandishing the soldering iron, I managed to cobble it together on some perfboard.

I added the decoupling capacitors he recommends as an addition to his design, and I have replaced R3 and R4 with 56.1k resistors to get near the time I need and adjust them from there. I am powering the whole shebang from a PC PSU.

Circuit schematics are a bit of a mystery to me, so I made the following assumptions - the relays both wanted the NC connecting to ground, and the switches had no polarity and needed connecting by the COM and NC tabs, with nothing on NO.

Powering up, the motor rotates counter-clockwise, then times out, but stays still until timing out again, at which time it resumes going counterclockwise. I can hear what I assume are the relays clicking.

So, I made it again, as I must have broken something, but with the same results.

Sadly, I have no idea what parts are meant to reverse the polarity to get the motor to go the other way, or if that's even the problem. Maybe I am a clumsy solderer and have broken the relays or something.

Could anyone suggest what may be wrong with the circuit, or more likely what rookie error I've commited? Thanks in advance!

Luke

Petkan:
The classical way of reversing anything is the bridge arrangement - in your case formed by two relay contacts (3 pins each).
As both relays are controlled in complementary way - you can use a single relay with two contact groups. It appears you also need limit switch operated by the motor hitting the mechanical constrains. Instead of mechanical relays you can also use solid state relays for instance opto-MOSFETs.. You can also use the limit switches to periodically reverse i.e. drop the 555. There is a family of Linear Techology chips collectively known as TimerBlox (LTC699X). They are way better than than 555 because the time is not based on capacitors and has just 1% part to part variation

 

"They are way better than than 555 because the time is not based on capacitors"

He is not trying to reproduce a cesium clock.

 

Another case for breaking the circuit into parts and testing each individually, then put it together.
As is, there are too many unknowns interacting. I would start just getting the motor to reverse and forward with the relay, then introduce the timer. Buffer each stage to take out interactions. Get it working, then simplify. Or be brave and go down the microcontroller route. No more trial and error with timings, outputs etc.

 

The op got his circuit to work.
Why are you beating a dead horse?

 

The op got his circuit to work.
Why are you beating a dead horse?

It's the only way to force them to drink.

 

So cup #1 (the top cup) tips over and pours its contents into cup #2. The motor running in one direction does this. Then the motor (that tips cup #1) reverses and stands the cup back up.

With this circuit the motor will be constantly running in one direction or the other. Constantly. All the time. If the cup tips over and hits a stop then the motor is trying to turn over a cup but can't move any further than the limit stop. Isn't the motor going to overheat?

Now, the next engineering challenge, turning cup #2 over and pouring its content into a mold. Are you going to build TWO circuits? If so, you can use a 556 (which is just two 555's on a single chip). But there's still the issue of motors running to their limit stops and then overheating. AND inside a vacuum chamber, there's not much air present to cool the motors. I'd be sure to examine that issue before moving forward.

Here's what I think you want: A motor to tip cup #1 over and hold that position without constantly hitting the limit. After a period of time the cup returns to the upright position. Meanwhile in cup #2 a mixer is mixing either the single compound or the two part mixture. After some period of time the cup is intended to pour its content into a mold. Here's another issue: The mixer. How do you remove the mixer from the cup before you tip it over?

I hate to be the guy who finds problems with the solutions, but to play devil's advocate, these are issues (and possibly others two) you need to contend with. It's one thing to build a timer that can reverse a motor every so-many seconds. it's another thing to build an automated mixing machine.

 

Tonyr1084, You are missing the fact that he has a limit switch at each end (S1 and S2) that stops the motor.
The motor doesn't reverse until the timer changes state.