Underwurldes - Diy Auto Top Off Project

[Underwurlde]

I could design a PCB for it and have it bashed up on the rapid prototyping machine here at work.....

problem with that though is that the design will be pretty much 'locked' and will me more awkward to develop (shall we say ) than prototyping it using strip board. Like I said, the circuit may well change from that shown because I have not tested it. (That'll be my excuse...)

Andy

 

[sophos9]

I could design a PCB for it and have it bashed up on the rapid prototyping machine here at work.....

problem with that though is that the design will be pretty much 'locked' and will me more awkward to develop (shall we say ) than prototyping it using strip board. Like I said, the circuit may well change from that shown because I have not tested it. (That'll be my excuse...)

Andy

Hell yea, design that PCB!!

What (if anything) do you think is most probable to change on that circuit? Should we just give it a go and get the PCB together, components in and cross fingers???

 

[sophos9]

I've just changed the title of this thread to something much more appropriate....

 

[Underwurlde]

'Professionally' I would design the schematic and then have it peer reviewed. If the PCB is simple (double) sided, I would get it prototyped here at work, build it and see if it works. When at an acceptable level of confidence in the design, I would have a proper PCB made by an external company and then test that again. (This job is 10% design, 90% testing).

Anyway, less waffle. If you want me to make a PCB for you I will – give me a couple of days, but as I said, bear in mind it may need tinkering with. Things I’d expect to alter? Well, the float switch for one (as I have catered for) and I’m not quite sure what happens when 555 timers are held in reset (Do the outputs go high or do they go low HOPEFULLY one would expect them to go LOW!!!!!). The datasheets for these devices are woefully inadequate for one, and also the last time I used a 555 timer was about 15 years ago (I consider them ‘hobbyist’ devices – but that’s just me being a snob).

The PCB will be correct to the schematic (if routed out correctly) as the PC checks this for you, so yes, bung the components in and away you go. I'll use through-hole components.

I WILL need a relay spec from you!

Andy

 

[sophos9]

I'm well jealous - what a job, I would love it!! I'm a Six Sigma Managing Consultant - wanna swop

I'm struggling on double pole, single throw 12v relays - the only ones I can find are 12v DPST reed relays but I think the ohms are a bit high? Loads of DPDT, are we able to ignore the DT?

Reed Relay


A sealed reedrelay
suitable for useat voltages from 3 8V to22V with single-pole make or double-pole make actions. The highresistance coil enablesthe relay to be drivendirectly by 74 seriesICs and most logic buffers. At the same time the relay can switch up to 10VA.
Contact Details (per contact)
Max current: 1A
Max voltage: 100V
Max switching power: 10VA
Contact resistance: 150mΩ max
Operate time: 1ms max including
bounce time
Release time: 0 5ms max including
bounce time
Life: >1 million operations
at full load

 

[Underwurlde]

Reed relays??? No,no & thrice no!

Anyway, SPDT or DPDT, makes no difference here. higher coil resistance the better (about 100ohms or more preferably / 100mA or less). Mains rated 240VAC contact of course, rated at about 1 Amp.

Just check - what current does the pump take?

Andy

BTW, the pay is pathetically poor. Engineering in the UK, pah. No worth, no pay. If I were anywhere else in the world I would be relatively rich, not struggling to pay off a 50K mortgage! Better off being a bloody train driver, so go figure!

 

[sophos9]

Reed relays??? No,no & thrice no!

Anyway, SPDT or DPDT, makes no difference here. higher coil resistance the better (about 100ohms or more preferably / 100mA or less). Mains rated 240VAC contact of course, rated at about 1 Amp.

Cool, found a 2A DPDT BT Type 47 Equivalent Relay

Contact details:
Maximum current: 2A
Maximum voltage: AC 250V, DC 220V
Maximum switching power: 125VA (A.C.)
60W (D.C.)
Contact resistance: <50mΩ
Operate time: 5ms max.
Release time: 3.5ms max.
Insulation resistance: 100MΩ at DC 500V
Mechanical life: >10 million operations
Electrical life >300,000 operations at full load
Contact material: AgPd and Au clad (Silver palladium alloy with gold overlay)
Coil details:
Nominal Coil
voltage resistance
DC5V: 167Ω±10%
DC12V: 720Ω±10%
Size of base: 20 x 10mm
Height of body: 9.9mm

Just check - what current does the pump take

The pump is 240v 5w, so 0.02amps...

BTW, the pay is pathetically poor. Engineering in the UK, pah. No worth, no pay. If I were anywhere else in the world I would be relatively rich, not struggling to pay off a 50K mortgage! Better off being a bloody train driver, so go figure!

Mate, sorry to hear that... Can you go self employed?

 

[Underwurlde]

Seems just the job. Point me to it then. (web addr or part #) and I'll do the rest.

Andy

 

[sophos9]

Seems just the job. Point me to it then. (web addr or part #) and I'll do the rest.

Here is the part...

Wish I had your brain, would be designing all sorts strange stuff for tropical/marine tanks, jesus with what you know, the possibilities are endless

 

[Underwurlde]

Yep, endless possibilities: my mind is constantly ticking away at ‘things’. But this kind of work does after a while wear you out, but I must admit, the novelty has definitely not worn out as I am constantly learning new stuff. Hell I have just designed a programmer for our existing product range and is based on a WinCE operating system and uses a 3.5â€￾ colour QVGA display – to think, I just designed a PDA!

Sorry, forgot, I also need to know which transformer you have in mind and the mains connectors.

Andy

 

[sophos9]

Yep, endless possibilities: my mind is constantly ticking away at ‘things’. But this kind of work does after a while wear you out, but I must admit, the novelty has definitely not worn out as I am constantly learning new stuff. Hell I have just designed a programmer for our existing product range and is based on a WinCE operating system and uses a 3.5â€￾ colour QVGA display �" to think, I just designed a PDA!

To me, thats crazy - people who are on the forefront of technology should be paid the required!! Freelance designer mate

Sorry, forgot, I also need to know which transformer you have in mind and the mains connectors.

Transformer is a 250ma, specs here
Mains connectors are euro female and euro male

Look OK?

Cheers

 

[Underwurlde]

Re: Transformer: Spot on specs, but would rather a PCB mounting one. Maplins don’t do them it would appear – look in RS / Farnell. Same goes for the mains sockets, would rather a PCB mounting one – but that actually depends on the box you are going to put it in.

 

[sophos9]

Hi mate,

Transformer from Farnell

Female Euro - Farnell

Male Euro - Farnell

As for boxes I have no idea - do you have any recommendations?

Thanks again

 

[Underwurlde]

VA rating == Watts. P=IV

Therefore P=?
I = 250mA (0.25) tops, with room to spare.
V = 15V

Hence VA rating = 0.25 x 15 = 3.75.

Hence need a transformer of about a rating of 3 to 4VA. (0.35VA will just fall on it's a$$).

(Don't worry if you can't find a PCB mounting transformer, it really is just a niceity).

Boxes are also in RS / Farnell.

Andy

BTW, just how much does a commercially available one of these things cost??

 

[sophos9]

(Don't worry if you can't find a PCB mounting transformer, it really is just a niceity).

Boxes are also in RS / Farnell.

Andy

BTW, just how much does a commercially available one of these things cost??

Nothing on Farnell... The commercially available SP3000 is £65 including the peri pump, the Tunz Osmolator is £99 for 2 optical sensors, alarm and LED indicators - also comes with pump Also has "An independent safety sensor with a separate power supply circuit and relay control ensures reliable overflow protection"

Do you think this will cost more?