Power supply issues

[Tinker1947]

Actually, it looks like those combined V/A digital meters have a separate feed to the voltmeter section from that to the ammeter.  I've ordered one to find out for sure.

i ordered 2 just in case one's not working.....

[Gina]

Actually, I have ordered 2 different ones

[Gina]

A dual V/A digital meter would be useful for the imaging power supply circuit.  The voltmeter would show the battery state while charging/discharging and the ammeter the load current when the load was switched on.  The current supplied by the PSU is shown on its own display.

[Ptarmigan]

  I've found a short length of black ABS extruded from the 3D printer so 0.4mm diamreter.

I wonder,

is it time to call in a goat to sacrifice a hair for the common good ?

I dont know the relative densities, nor the stiffness of goat hairs, you may have to catch a brush instead !

Can you even remove the ABS without further jeopardy ?

[Gina]

I wonder,

is it time to call in a goat to sacrifice a hair for the common good ?

I dont know the relative densities, nor the stiffness of goat hairs, you may have to catch a brush instead !

Can you even remove the ABS without further jeopardy ?

Might be possible but I've gone right off the idea of using an analogue meter

[Tinker1947]

How about MCB's get into the 21st Century....

[Gina]

I think the power and focus control box is ready for testing having almost finished wiring.  The box that goes in the warm room to connect the PSU and battery to feed the imaging rig is ready for wiring up.

I don't think I shall be ready for imaging out in the observatory for a day or two yet BUT... I have put the EQ8 mount that got drenched when the roof blew half off in the stroms a few days ago, back together after drying out and it seems alright   Forecast says possible clear spells tonight but I don't think I'll be ready and I've learnt not to rush it

[Gina]

Just been working how to connect the little power box for the imaging rig (yellow box above).

[Gina]

Inside of the power box - nearly finished wiring up.  The output to the cable that feeds the imaging rig connects to terminal marked 3 on the switch (bottom one in the photo) Positive and the thick red wire from the ammeter which is the Negative.  I shall need a connector - probably use a choc block type though the positive could be a spade connector that goes on the switch.

[Gina]

SketchUp design for the lid/back.

[Gina]

Printed the lid/back plate for the battery fuse and switch box for the imaging rig power.  Connected red wire onto the switch and black wire to the red wire (shortened) from the ammeter and brought these out of the back where they can be connected to the cable with a choc block.

Photos show the back of the yellow box and wiring to the PSU and battery.

PS200T PSU and battery connected to the switch and fuse box.  Output switched off - ammeter unpowered.

Output switched on - ammeter powered and displaying the load current.

[Gina]

A photo I missed - the wiring of the fuse and switch box.

[Gina]

Now at the testing phase of the power and focus control box and associated stuff.  The power side is fine - all checked out - but i have a fault on the focus control.  I have tracked this down to a faulty 3.5mm stereo socket on the remote control box.  When the plug is inserted into the socket one of the contacts shorts out to the case (gnd)   Unfortunately I can't see what's going on (or fix it) because it's a screened socket with a solid metal case that's spun over to hold the plastic inner.  I guess I could get inside with a hacksaw but may not be able to fasten it back together - though hot glue comes to mind

Now I'm having a search to see if I've got another stereo socket.  Or I could canabalise a lead perhaps

[Gina]

Having failed to find another 3.5mm stereo socket, I decided to butcher the original with a hacksaw to gain access.  I found the problem - longer contact (which connects to the ring of the plug) was touching the case, in spite of there being an insulating plastic tube.  The cure was to snip a little bit off the tip of the contact.  I have now assembled the socket, put it back in the box and connected up and plugged in the 5m cable I shall be using.  The measured resistance at the far end of the cable now shows the correct values for the various combinations of switches and buttons.  So ready to test the main Arduino box. 

Since the original case connection was sawn off I have wrapped tinned copper wire round the case and soldered it on to provide the ground connection.  Now I just have to glue the insides back into the case and check all is still well.

[NickK]

Hi Gina - computer power supplies, from experience, are shockingly over quoted for the current capacity of 5V and 12V lines. From PC overclocking, one thing that would happen is that power draw on one line would cause most average PSUs to drop their other lines too.

[Gina]

Hi Gina - computer power supplies, from experience, are shockingly over quoted for the current capacity of 5V and 12V lines. From PC overclocking, one thing that would happen is that power draw on one line would cause most average PSUs to drop their other lines too.

Just as well I've stopped using one then

[Gina]

The correct voltages are showing on the Arduino analogue input pins but the stepper motors aren't responding correctly   Some very strange results   The fast forward is making all motors turn.  Now the serious Arduino sketch debugging begins...

[Gina]

Found a couple of mistakes in the sketch but now I can't get the PC to connect to the Arduino USB.  It's powering the Arduino but the USB is not being found.  I've tried rebooting the PC and another USB port but no joy.  I HATE USB!!!   

Anyone got any ideas, please?

[Gina]

I think the power side of this is now covered except for the results once I get all the kit reinstalled in the observatory.  To be sorted out now is the focus control system which is a different topic really so I think I'll start another thread for this.

[Gina]

I've decided to separate the power distribution from the Arduino focussing system.  It seemed a good idea to put everything in the one box but I've changed my mind now   Faultfinding is easier if they are separate.

For the time being I have just taken the Arduino out and disconnected the power for the drivers.  That saves unsoldering all the power components to put them in a new box.  With a forecast clear sky tomorrow night I want to be ready if I can.  I'll redo the box later on (if it's worth bothering).  That leaves just the Arduino to be accommodated in a new box.

[Gina]

Now have the main rig set up on the EQ8 mount.  That's MN190, Esprit 80ED and ST80 ATM.  460EX imaging cameras on Esprit and ST80 and Lodestar X2 guide camers on MN190.  New power boxes seem fine   Have been aligning the scopes on a pair of security lights on a garage on the far hill.  Have adjusted sideways and now need to pad out one of the ST80 rings to get up/down alighment.  I may arrange a screw adjustment later.

Photos to follow (probably)...

[Gina]

The good news is that the Lodestar X2 guide camera is showing no problems and is guiding well   So that's been fixed by improving the power supply

The bad news is that my new remote focussing box is refusing to work properly in the observatory though it works fine indoors   Now that's a puzzle

[Gina]

Here's a screenshot of the PHD guiding graph.

[russellhq]

What scale is the graph? It's hard to tell from the screenshot.

[Tinker1947]

shows 100 on my monitor...