DIY power box ?

[Gina]

I concur precisely Ray as a previously qualified professional electrical and electronics engineer.

[BRUN]

I did buy fast blow, ill see how I go

[RayD]

5 minutes ago, BRUN said:

I did buy fast blow, ill see how I go

Ok they will possibly blow as they're not really designed for inductive loads but as you say see how you get on and if they do blow just use a general or "G" rated fuse.  If that fails use a "T" rated one.  You'll get there eventually 

[RayD]

25 minutes ago, Gina said:

I concur precisely Ray as a previously qualified professional electrical and electronics engineer.

I wondered why you seemed so good at system designing and programming.  Now answered 

[SonnyE]

My AVX mount came with a "cigarette" type 12 volt power cord. In the nose of it lives a 5 amp fast blow glass fuse. And it's blown a few of them when the motor drives have failed.

I went to a local store called Radio Shack and bought replacements. Since the second warranty repair I've fed the mount only battery power and have had no further troubles. Batteries produce pure DC power.

My CCD's cooling system likes a 2 amp protection, but it has never had a problem.

As Ray said, the fuses are for circuit (wiring) protections, not the electronics. In my experiences, by the time a fuse goes there is already some serious troubles in the components (smoked parts). Changing the blown fuse will usually get the user nothing more than another blown fuse.

[cjdawson]

When I built my power box, dew controller and power distribution box projects I put in lots of fuses.  Precisely for the reason that is something blew a fuse, I would know quicker were to look be the device that had powered down.   This came into it's own, when I was at a star party and found that I'd messed up one of the connectors - there was a single strand of copper wire from a multi strand core loose.  It had decided to cause a short circuit months after I'd built the project.  The 2A fuse for my mount blew, I realised it was the mount that had failed. Then took to the project with a screwdriver and a multi meter to find the problem.  On seeing the blown fuse, I replaced it and the next fuse blew.  At that point, I pulled out my spare mount power cable and attached that.  On knowing that the mount was fine, I started to dismantle the power connector and found the rogue wire.   I snipped off the loose strand, then added a little electrical tape.  It's been fine ever since.

 

To that end, I designed in lots of fuses into my project....

 

Power distribution box, has 3 * 2Amp quick blow fuses, these are for each of the 12v power outputs that can be used for the main scope and accessories.

The dew controller box, well it's more than that has fuses for each of the two dew heaters. A few that feeds the 12v power distribution box, and a fuse for the 5V power that runs to the same box.  I'm going to be adding an 8V at some point, and that will be fused too.

 

My battery box is a project in itself and again has lots of fuses.

 

4 * cigarate sockets (each fused to 10amp, wiring rated for 20amp, but the crimps and the sockets are rated for 10)

2 * 2USB - I think these have 5 amp fuses. The wiring is rated for 20amp, but 5 is slightly more than the USB will consume.

1 * telescope power - this is a 10 amp fuse.  When everything is running on my scope, I think I'm pulling about 5 amp if I really try.  This is overrated, but there is overhead for more accessories later on.

 

I'm sure that if I tried, I could work some more fuses into the project, seems to be good enough protection though.

[iapa]

On 08/01/2017 at 17:17, BRUN said:

Cheers

Does it make any difference whether you have male or female on the box and vice versa ?

I would say that generally the side sourcing the power is female

means you can't short it accidentally

[iapa]

sorry, should have said" reduce chance of shorting, not that you cant - people can be vey inventive in that regard  

[RayD]

2 hours ago, cjdawson said:

I'm sure that if I tried, I could work some more fuses into the project, seems to be good enough protection though.

You can't have too many fuses, but you can most certainly have too few.  Glad you had yours there to save the day 

[SonnyE]

Another quick tip for all of us D.I.Y'rs...

If you have a lot of fuses in your project, you may want to make an indication for them so you can find a dead one easily.

Tiny LED's added on the load side of your fuses can go to an Off state if the supplying fuse blows. No Glow = No Go. (Example 1, EXAMPLE 2) (This, I find, can be useful for my aging eyes, or where there is an abundance of fuses.)

I mean, if you want sexy in your power supply, this is Wow factor.

(I simply use my eyes, or one of my meters...)

[Marci]

Or... use blade fuses n’ these! (wish I’d spotted them when I made mine)

Singles: https://www.amazon.co.uk/Waterproof-Inline-Blade-Holder-Indicator-x/dp/B00A2PBE6M

Multiples: https://www.amazon.co.uk/6-Way-Illuminated-Blade-Holder-Cover/dp/B012IDBXZC/ref=sr_1_1?s=electronics&ie=UTF8&qid=1484260370&sr=1-1-spons&keywords=blade+fuse+holder+led&psc=1

[RayD]

9 hours ago, Marci said:

Or... use blade fuses n’ these! (wish I’d spotted them when I made mine)

Singles: https://www.amazon.co.uk/Waterproof-Inline-Blade-Holder-Indicator-x/dp/B00A2PBE6M

Multiples: https://www.amazon.co.uk/6-Way-Illuminated-Blade-Holder-Cover/dp/B012IDBXZC/ref=sr_1_1?s=electronics&ie=UTF8&qid=1484260370&sr=1-1-spons&keywords=blade+fuse+holder+led&psc=1

The second one is exactly what I have in my battery box. Works well 

[iapa]

9 hours ago, Marci said:

Or... use blade fuses n’ these! (wish I’d spotted them when I made mine)

Singles: https://www.amazon.co.uk/Waterproof-Inline-Blade-Holder-Indicator-x/dp/B00A2PBE6M

Multiples: https://www.amazon.co.uk/6-Way-Illuminated-Blade-Holder-Cover/dp/B012IDBXZC/ref=sr_1_1?s=electronics&ie=UTF8&qid=1484260370&sr=1-1-spons&keywords=blade+fuse+holder+led&psc=1

I just got y self something similar, just looking to the 300mA, 500mA fuses now.

[iapa]

12 hours ago, SonnyE said:

Another quick tip for all of us D.I.Y'rs...

If you have a lot of fuses in your project, you may want to make an indication for them so you can find a dead one easily.

Tiny LED's added on the load side of your fuses can go to an Off state if the supplying fuse blows. No Glow = No Go. (Example 1, EXAMPLE 2) (This, I find, can be useful for my aging eyes, or where there is an abundance of fuses.)

I mean, if you want sexy in your power supply, this is Wow factor.

(I simply use my eyes, or one of my meters...)

any recommendation for these - preferable with integral resistive load to minimise current draw when in parallel across the supply.

 

ta

[RayD]

This is my one.  It gives you the ability to add new items and plugs etc. in the future.

 

 

[iapa]

Duh!

I got one with out indicators; didn't even think to look for one with integral LEDs

[RayD]

5 hours ago, iapa said:

Duh!

I got one with out indicators; didn't even think to look for one with integral LEDs

TBH if you have a separate circuit for each item, and you write a little fuse chart down to stick next to the holder with the fuse value and what it serves, then you'll know which one has gone anyway, so I shouldn't worry about it.  It's a nice to have but not really essential.  From memory on mine (not used it for a while so can't remember for sure) the LED comes ON when the fuse blows, which is actually better as you don't have 10 LED's on all the time.

[RayD]

Don't forget though I don't think you'll get 500mA fuses in blades, unless someone can post a link to them.  I think the lowest value is 1A (black) which should do for pretty well most things you're going to use.

[Gina]

Yes, that's what I thought but I agree 1A fuses should be fine for light loads.  The main use of a fuse is to protect the wiring.

[Marci]

2 hours ago, RayD said:

Don't forget though I don't think you'll get 500mA fuses in blades, unless someone can post a link to them....

https://www.amazon.co.uk/Fuse-0-5-Blade-Fuses-8820/dp/B00IZCFT24 

Admittedly, that's the ONLY one I could find, anywhere...

[Gina]

What a ridiculous delivery price  

[RayD]

21 minutes ago, Gina said:

What a ridiculous delivery price  

Good find I've never managed to find any, but as Gina says OMG delivery price

 

[SonnyE]

I absolutely abhor people who gouge you on Shipping and Handling (delivery) prices. So much so, I look elsewhere for my supplies, and only come back to them if necessary. It is enough that you are buying their goods, without making you buy their lunch as well.

10 hours ago, iapa said:

any recommendation for these - preferable with integral resistive load to minimise current draw when in parallel across the supply.

iapa,

Hi. Yes many places carry integrated LED's (resistors built in) where all you need is to apply a source. I've even found some Micro LED's that blink.

My original thoughts were along this line for the indication for a blown fuse. But it presents the problem of if the downstream circuit that blew the fuse in the first place is open, there is no indication. So slightly more sophisticated circuitry would be needed. And I like simpler solutions myself.

I think the blade fuse holder W/indication is probably the best idea presented here so far. It's a nice modular unit for folks building their own customized power supplies, which I think is a majority here.

Any sort of visual indication where a fuse is used is an advantage over poking around with meter leads testing them.

[SonnyE]

I might add: I'm still using the original cigarette plugs so I can hopefully use them from my truck if/when I go out to a remote site. (And even when I have, I just use my big battery anyway.)

But I've been happy to stay at home so far. And haven't needed to change my methods of feeding my mount and CCD cooling power.

I suppose I am in a rut. A comfortable rut...

[iapa]

2 minutes ago, SonnyE said:

But I've been happy to stay at home so far. And haven't needed to change my methods of feeding my mount and CCD cooling power.

TBH if I can continue to be able to catch things like this from the back garden, that I can use to refine everything else, I'm probably not going got need portable power - unless I go to a star party (when I can get the time).

Even then I'd be looking to just run the car