The E-drive (V3) + PDF

[AUS]

Re: The Elasti-drive Intro (V1 and V2)

I've had problems with small trimpots on cheap chinese driver boards moving in use and killing diodes, I always put a dob of nail polish on them now once they are set to keep them there.

I'm thinking these boards are a bit small for a multi turn pot though.

 

[Hiemal]

Re: The Elasti-drive Intro (V1 and V2)

Yeah, I'm trying to figure out a few ways to get around this....

I can't fit a multiturn pot on here, as much as I wish I could. I'm really pissed off at newark, though, since they basically lied about that.

Either way though, I'm tempted to figure out how hard they are to adjust with one pot, and if they are difficult, we're prooobably going to go with two jumpers; one for high and one for low, with a different value potentiometer. Thank you ben for pointing that out to us...

 

[RA_pierce]

Re: The Elasti-drive Intro (V1 and V2)

Personally, I like not having a pot. I always worry about breaking them or wearing them out while I am trying to set the current... And it's hard to get it exactly where I want it.

This used to be a DIY hobby. Not many here have the electrical engineering knowledge and experience to design drivers but soldering a couple resistors should not be a big deal IMO. Selling the drivers with the appropriate resistors for whatever current and requiring the user to solder them on might encourage more people to practice their soldering skills. Sure a pot is more "user friendly" but it just doesn't seem practical.

Personally, I'd have no problem with fixed currents. Pots are nice when I am aiming for a specific power output but other than that I don't see a benefit.

Fixed resistors are just more practical considering size, cost, and robustness.

 

[laserluke]

Re: The Elasti-drive Intro (V1 and V2)

So, me and Tsteele have been working more or less all summer, and into college for me on this driver.

Nice job :beer:
Good implementation of the TPS63060 with high side current sense (the feedback network of this chip is the same of the TPS63020).
I would suggest to you to improve the pcb layout by reducing the number of vias and leaving more space for the thermal pad below the chip on the pcb bottom side.
You should leave a solder resist free zone on the bottom side just below the chip because its thermal resistance juction-to-case(top) is 54.8°C/W whereas junction-to-case(bottom) is only 4.2°C/W.
-Luke

 

[tsteele93]

Re: The Elasti-drive Intro (V1 and V2)

Nice job :beer:
Good implementation of the TPS63060 with high side current sense (the feedback network of this chip is the same of the TPS63020).
I would suggest to you to improve the pcb layout by reducing the number of vias and leaving more space for the thermal pad below the chip on the pcb bottom side.
You should leave a solder resist free zone on the bottom side just below the chip because its thermal resistance juction-to-case(top) is 54.8°C/W whereas junction-to-case(bottom) is only 4.2°C/W.
-Luke

That should actually implemented in the next boards coming in, hopefully this week. These are all larger preproduction boards we're showing right now. We were able to go with a smaller capacitor on the output which helps reduce size a good bit.

We really appreciate the tips! We have implemented some already, but others are definitely being considered and I'm sure the board will continue to evolve.

I believe one reason we added so many vias was FOR a heatsinking effect. Do you think that is a bad idea?

Also, we both want to be VERY clear about the Pre-production boards we are selling at a discount. They are fully guaranteed with your money back if you experience any type of failure.

ALL you have to do is drop the driver in an envelope with std first class ($0.45) postage and get in touch with us so we know what happened and can try and look into the problem when we get it back.

You are only on the hook for the stamp and envelope to get it back to us answer will refund any outbound shipping as long as you did not use expedited shipping.

We will honor this warranty for AT LEAST 90 DAYS and possibly (probably) longer if there is a fair reason for the return. We want this experience to be a positive one and right now it isn't about making money, right now it is about making a great laser driver. Once that is sorted out, the money will work itself out.

We trust that no one will take advantage of the guarantee and send back drivers that they know they killed. And the driver has a LOT of protection, over voltage, under voltage, thermal protection, reverse polarity protection and more. This should be a VERY hobbyist-friendly driver.

Please understand that this is our first undertaking, so we may have some mis-steps, but we plan to handle them in a way that will inspire confidence in our product and more importantly - our service!

 

[Meatball]

Re: The Elasti-drive Intro (V1 and V2)

Personally, I like not having a pot. I always worry about breaking them or wearing them out while I am trying to set the current... And it's hard to get it exactly where I want it.

This used to be a DIY hobby. Not many here have the electrical engineering knowledge and experience to design drivers but soldering a couple resistors should not be a big deal IMO. Selling the drivers with the appropriate resistors for whatever current and requiring the user to solder them on might encourage more people to practice their soldering skills. Sure a pot is more "user friendly" but it just doesn't seem practical.

Personally, I'd have no problem with fixed currents. Pots are nice when I am aiming for a specific power output but other than that I don't see a benefit.

Fixed resistors are just more practical considering size, cost, and robustness.

I don't know about you, but I'm not about to get out my pencil tipped iron to try and make smd connections with it. I would have to buy some solder paste and the then bake the board. I would not want to do that either since its a two-sided board. Many people don't have nice vices, and magnifying glasses to get something that small on something they already bought.

If someone is going to spend $20 on a <12mm driver, should it not at least be complete in one piece? Ready to use? I think these tiny pot serves their purpose just fine. If you really HAVE to have your current setting to be perfectly within 15mA, then I suppose there are plenty of other drivers capable of doing so.

I think the purpose of this driver is centered on flexibility in a cost effective package. Something will have to sacrificed to make that happen.

 

[Hiemal]

Re: The Elasti-drive Intro (V1 and V2)

I'm quite sure we will sell fixed versions along with the adjustable ones, so don't worry about this guys.

We're attempting to work out a compromise on this, so we'll let everyone know what the plan is.

 

[RA_pierce]

Re: The Elasti-drive Intro (V1 and V2)

I don't know about you, but I'm not about to get out my pencil tipped iron to try and make smd connections with it. I would have to buy some solder paste and the then bake the board. I would not want to do that either since its a two-sided board. Many people don't have nice vices, and magnifying glasses to get something that small on something they already bought.

If someone is going to spend $20 on a <12mm driver, should it not at least be complete in one piece? Ready to use? I think these tiny pot serves their purpose just fine. If you really HAVE to have your current setting to be perfectly within 15mA, then I suppose there are plenty of other drivers capable of doing so.

I think the purpose of this driver is centered on flexibility in a cost effective package. Something will have to sacrificed to make that happen.

I've repaired a couple Flex V5s with my crappy $15 soldering iron from Home Depot and some fine tipped tweezers.

I agree that something has to be sacrificed and like you said, cost is one of the important factors...
If that is the case then an expensive and bulky potentiometer seems like a poor choice.

Fixed resistors keeps the size and cost down and makes the driver more robust. The only sacrifice is that adjusting the current is a little more difficult. While my iron is already hot, swapping out a couple resistors is not a big deal. At least to me.

I'm not saying pots are bad. I'm just saying that they're not that great. I would gladly solder on my own resistors in exchange for some saved $ (if the difference is significant).

If the original design uses a pot that wears out in 20 or so turns, that is ok, too. I don't see why someone will need to change the current 20 times.

Anyway this is just IMO.

 

[Hiemal]

Re: The Elasti-drive Intro (V1 and V2)

Really, the only problem that I see in utilizing the current design, is current precise-ness.

With 20 turns and 100k, it would've been very very easy to select a specific current.

100k and 1 turn, it might be a bit difficult, but we're going to test it out and see how bad it is. Hopefully it'll be doable!

 

[laserluke]

Re: The Elasti-drive Intro (V1 and V2)

A very useful feature that can be added to this driver is a current monitor output.
If you use a second current monitor ic (with fixed gain...) connected to the output shunt resistor as the one used for the feedback (in parallel...) you will have an additional output that can be used to measure the output current without the need to disconnect the laser diode and insert an ampere meter.
-luke

 

[Hiemal]

Re: The Elasti-drive Intro (V1 and V2)

A very useful feature that can be added to this driver is a current monitor output.
If you use a second current monitor ic (with fixed gain...) connected to the output shunt resistor as the one used for the feedback (in parallel...) you will have an additional output that can be used to measure the output current without the need to disconnect the laser diode and insert an ampere meter.
-luke

... Um, that's kind of what test loads are for, anyway.

It wouldn't make much sense to add more to the board, and make it bigger for something that's unnecessary.

 

[Meatball]

Re: The Elasti-drive Intro (V1 and V2)

I've repaired a couple Flex V5s with my crappy $15 soldering iron from Home Depot and some fine tipped tweezers.

Damn. It sounds like I've got something to learn. You've got my respect for some mad soldering! :beer:

 

[tsteele93]

Re: The Elasti-drive Intro (V1 and V2)

A very useful feature that can be added to this driver is a current monitor output.
If you use a second current monitor ic (with fixed gain...) connected to the output shunt resistor as the one used for the feedback (in parallel...) you will have an additional output that can be used to measure the output current without the need to disconnect the laser diode and insert an ampere meter.
-luke

Luke, that is a cool idea! I just don't know how much space it would take? We are trying to go smaller, smaller, smaller! I'm putting that down as an idea for later!

Tom

 

[tsteele93]

Re: The Elasti-drive Intro (V1 and V2)

Personally, I like not having a pot. I always worry about breaking them or wearing them out while I am trying to set the current... And it's hard to get it exactly where I want it.

This used to be a DIY hobby. Not many here have the electrical engineering knowledge and experience to design drivers but soldering a couple resistors should not be a big deal IMO. Selling the drivers with the appropriate resistors for whatever current and requiring the user to solder them on might encourage more people to practice their soldering skills. Sure a pot is more "user friendly" but it just doesn't seem practical.

Personally, I'd have no problem with fixed currents. Pots are nice when I am aiming for a specific power output but other than that I don't see a benefit.

Fixed resistors are just more practical considering size, cost, and robustness.

Just to confirm what LeQuack said, there will be a fixed output version. Heck, those are the easiest to make! We are just trying to offer a pot version for the hobbyist who likes being able to make the calls right there in the bench in front of them as they put a laser together.

 

[foulmist]

Re: The Elasti-drive Intro (V1 and V2)

I knew they didn't look like 20 turn pots but that's not Newark's fault. It is actually written in the datasheet of the pot too. Rotational Cycling - 20 turns. :crackup:Go figure what this means. Both descriptions are misleading as both may refer to no. of turns and maximum no of turns a pot can handle before it is useless ...

but remember that this type of pots are always 1 turn.

 

[laserluke]

Re: The Elasti-drive Intro (V1 and V2)

You can use just a single ZXCT1021 and no other components...
I think that this is really useful for any user. You can mount your build (driver, laser diode, heatsink, host etc.) and set or change the desired current without the need to further disconnect the diode from the driver...
-luke

Luke, that is a cool idea! I just don't know how much space it would take? We are trying to go smaller, smaller, smaller! I'm putting that down as an idea for later!

Tom