Alx's LD CURRENT DRIVER (30mA-800mA/5V-16V)

Driver Test

First... Alx... sorry this took so long... I've been swamped with work...

Well... I finally found some time to test "Alx's" driver...

First let me say that even though the "Alx" and "rkcsr" (old) driver seem to
look the same... they are not the same PCB or Layout..IMHO

The printed circuit board traces are not identical and they do not run
the same routing paths..

The electronic parts used may have a similar function... but they are not the same....

The "rkcsr" PCB measures 0.361" X 0.695" and is manufactured on .031" thick board
The "Alx driver measures 0.375" X 0.700" and is manufactured on .062" thick board

So much for the visual....

I used a 6 diode test load with a 1 Ohm resistor in series... I supplied 9VDC
from a variable Power Supply..(so that the supply would not sag as with batteries)
I check the output current and voltage.. The PCBs were on an insulated surface
in free air (no heatsinking)..

First the "rckstr" driver...

027 ma ............. 4.29 Vdc .............. Min Pot setting
050 ma ............. 4.53 Vdc
100 ma ............. 4.75 Vdc .............. starting to warm up
150 ma ............. 4.87 Vdc
200 ma ............. 4.94 Vdc
250 ma ............. 4.96 Vdc
300 ma ............. 5.99 Vdc .............. Very hot to the touch
417 ma ............. 5.14 Vdc .............. Max Pot setting

It should be noted that it was next to impossible to adjust the current
accurately obove 200ma.

Now for the Alx driver...

029 ma ............. 4.37 Vdc .............. Min Pot setting
050 ma ............. 4.55 Vdc
100 ma ............. 4.76 Vdc .............. starting to warm up
150 ma ............. 4.88 Vdc
200 ma ............. 4.99 Vdc
250 ma ............. 5.00 Vdc
300 ma ............. 5.04 Vdc .............. quite hot to the touch
500 ma ............. 5.30 Vdc .............. Very hot to the touch
560 ma ............. 5.33 Vdc .............. Max Pot setting (stabalized Hot)
608 ma ............. 5.56 Vdc .............. Max Pot setting (PCB Hot)
701 ma ............. 5.70 Vdc .............. Max Pot setting (PCB Cold)

It should be noted that it was next to impossible to adjust the current
accurately above 400ma. That may be due to the physically larger pot used.
The current at the maximum setting decreased as the PCB heated up from
the higher current draw...
When I gently blew (without spitting:na onto the PCB.. the current started
to increase immediately..

I haven't seen the schematic of the Alx driver so I can't comment on that...

To sum it up... in my honest opinion...
The "Alx" and old "rckstr" drivers are 2 different Laser Diode drivers of different
output ranges... One is not better than the other for what it was designed...


Jerry

ElektroFreak said:

Finally got around to trying out my driver. I'm using it to power an LOC diode at 320mA, with 9V on the input. There is a little heating at this current setting, but that is to be expected. The driver functions perfectly, and is of very good build quality. For the price they are an EXCELLENT deal. Highly recommended.

Click to expand...

Hi ElectroFreak,

I'm glad that you finally have it working. Thanks for your positive feedback. Is exactly as expected ans stated in its techical specs. And don't forget. Recommended input voltage for LPC-PHR, GGW, GBW diodes is 2 LI-Ion accumulators, (7-8V) because else the supplementary voltage will be converted in more heat. Higher currents and input voltage is not for our present needs. Has been designed for expensive 500mW Sony diodes which work over 600mA! Anyway, at your rates (3-400ma), heat should not be a problem anyway!

Cheers,
Alx

lasersbee said:

500 ma ............. 5.30 Vdc .............. Very hot to the touch
560 ma ............. 5.33 Vdc .............. Max Pot setting (stabalized Hot)

Click to expand...

PERFECT: I dont have technical specs in front or me, but around 500mA is the higher load, SO DRIVER WORKS AS EXPECTED AS TIME AS AT 560ma heat has been stabilized value! USE SWITCHING OR HEATSINKING, will work better!

lasersbee said:

608 ma ............. 5.56 Vdc .............. Max Pot setting (PCB Hot)
701 ma ............. 5.70 Vdc .............. Max Pot setting (PCB Cold)

It should be noted that it was next to impossible to adjust the current
accurately above 400ma. That may be due to the physically larger pot used.

Click to expand...

No, definitely is not a problem. I have a lot here driving at 408-410ma. Maybe is just a non conform potentiometer (very rare case - under 1% from total produced drivers), but I am sure that if you will try again, you will get 400mA rates without problems. You should be carrefully when adjusting (the pot is thin and very sensitive), because we are operating with fractions of Ohms (has been stated too on my first post).

And other thing which I forgot to mention but worth to be mentioned here is ABILITY OF THIS DRIVER TO REMAIN COLD at lower (under 120-150mA - all blue ray diodes) and higher (over 550mA - powerfull red diodes) currents even NO HEASTINK OR NO SHITCHING IS USED!!! Even at 410-420mA (red LPC diode), the heat is not sesisable at all if you use duty cycles or other methods to dissipate a little the heat! This information has been already given when I said that I am using it on my red lasers driven at 410mA, and used combined heatsink (AX/DX case plus flashlight case) and the heat can't be felt by hand!

lasersbee said:

The current at the maximum setting decreased as the PCB heated up from
the higher current draw...

Click to expand...

Does it mean that is working EXACTLY as has been designed. You are not using heatsinking (to keep the temperature as stable as possible or at lower rates) and this circuit has termal and overlod protection BUILT-IN. So, is absolutely normal and a superb feature.

lasersbee said:

When I gently blew (without spitting:na onto the PCB.. the current started
to increase immediately..

Click to expand...

Again, is a normal thing. You must use a heatsinking/switching (like me, combining AX/DX case, with flashlight case). But even without that, this driver proved to be very strong. I SAID VERY CLEAR on page one THAT A DUMMY DRIVER (WHAT YOU USED) WILL NOT BE PROBATIVE! With just a little heatsink will work very well even at higher currents (over 500mA). Also, at higher currents, laser diodes need hetsinking/duty cycles first (read the sony specs which speak very clear about that). So, is not a driver problem. You forced its limits as worse as possible environment/conditions, and even in this worse scenario, has been survived... Good! Very good, and nothing unexpected for me. I said that all components inside are heat resistant!

lasersbee said:

To sum it up... in my honest opinion...
The "Alx" and old "rckstr" drivers are 2 different Laser Diode drivers of different
output ranges... One is not better than the other for what it was designed...
Jerry

Click to expand...

I think that anybody read above values and my specs, will have another opinion regarding this driver (is better price and quality than other). And of course, the scope has been THE SAME: to have a driver for LPC, PHR, GGW, GBW diodes, so your conclusion is just strenghening what has been already specified (I dont want to reinvent the wheel ....). But again, here is not a competition. And also, I never go to other peoples threads, and post there something about this driver, like someone here does, complaining naive things (in general to confuse users, and sustain his business)! Also, the price is very low. At 6USD, will be very difficult for anybody else to produce and sell it in very small quantities (under 100pcs/order). Just think about: has been designed only for our lpf users, not for outside market. I saw that someone here, is organizing presales, because does not have enough money to sustain entire manufacturing process... want to organize Group By, or other crap. And for those which want to know, when are you designing such circuits, BUDGET WILL EXCED 5-10.000EUR if you want to have it at lower rates, like I proposed.

So, how will be if WILL NOT BE ANY PRESALES, or GROUP BUY? Very well, right? Why to reinvent the wheel, as time, we already have a STRONGER DRIVER/BETTER QUALITY available in small quatities (very small orders): just 2-400USD/order!!!! Very well, right?

Think about, what's happend here, till my appearance. This driver cost over 15-18USD/each!!! NOW, IT IS ONLY 6USD (tested, assembled, tracked, insured)!!! How much money want someone to earn, selling this piece? Hard to understand. How much money want someone to invest when at only 350USD, you can have it all in your hands, without any other effort?

You got idea, right?! And I dont want to be caustic, saying somethnig about difference from 6USD (better quality) up to 18USD (lower quality)!!! Also, if someone try to produce it at lower rates (under 6USD), how much money do you think that will earn? How much money do you think that must be invested? I already quoted above ... Again, here was a jungle till my appearance, and even I'll not sell someting, I know that in the future, the one which will try to produce it, WILL BE FORCED TO SELL IT UNDER 6USD, AND MAKE IT BETTER (technical speaking). So, I already have a satisfaction: no matter who will produce it, is a certain thing that WE ALREADY HAVE a cheap driver!!!!

And personally, I think that 6USD, will be a harder limit to jump over ...

Regards,
Alx

Hey Alx....

Originally Posted by lasersbee
608 ma ............. 5.56 Vdc .............. Max Pot setting (PCB Hot)
701 ma ............. 5.70 Vdc .............. Max Pot setting (PCB Cold)

It should be noted that it was next to impossible to adjust the current
accurately above 400ma. That may be due to the physically larger pot used.

Click to expand...

You misunderstood what I meant.... (you're very defensive)

The pot on "rckstr" driver started to be difficult to adjust precisely at around
200ma and yours only became difficult to adjust precisely at around 400ma...
I attributed that on (perhaps) the physically larger pot on your driver...

Both drivers seemed to heat up the same amount at the same current setting..
which makes sense since both have about the same surface area...
The Alx driver of course heats up a bit more at 500ma...

I think I did a fair and honest test of both drivers... without taking sides and
yet you seem to find the need to question and restate facts in the tests...
like no-one understands...

I take offense that you can't just accept the review I did... but need to scrutinize
it as well... The test speaks for it's self... a simple "thanks" would have sufficed...

You seem to be very defensive and I have said nothing against either driver...

For you to keep ranting that yours "is better price and quality than other" is
just not completely true...
It may be cheaper... but with the new "rkcstr" silk screened PCBs... I think the
quality of the "rkcstr" PCBs is better...
The rest of the electronic parts (that neither of you manufactured) are the same
quality....

When I see a statement like "here was a jungle till my appearance"...
I see that you think very highly of yourself.. not a trait that inspires me...
Had I known that about you before.. I would have surely declined to do
the tests.....

I understand that you are trying to sell your drivers here... and you have
the right to do so....
but I believe you are going about it the wrong way by attacking the "rkcstr"
drivers...

"rkcstr" has been selling his drivers here for quite some time... and has gained
a lot of trust and respect here...
Be carefull that your sales pitch does not backfire in your face... members here
are loyal............

BTW... The only technical specification difference between the two drivers that
I could see is that your Driver goes above 400ma to at usable max 550ma...
as I tested them...

Other than that.... they both do the same job...

(I may have misunderstood your post due to the language barrier.....
but I doubt it...:undecided


Jerry

lasersbee said:

Hey Alx....
For you to keep ranting that yours "is better price and quality than other" is
just not completely true...
It may be cheaper... but with the new "rkcstr" silk screened PCBs... I think the
quality of the "rkcstr" PCBs is better...
The rest of the electronic parts (that neither of you manufactured) are the same
quality....

Click to expand...

I thought you understand that our relation has ended when you didn't respected our convention which you agreed (to notify me first, before you post here). Even your test is in general positive, are other considerations which are gratuitous or wrong!

I dont want to comment in any way your afirmations regarding "same quality components" and "other pcb is better". Are just speculations without arguments (and yes, I'll not go ahead to polemize with you about this subject. Are your opinions. I told you that I don't like noise). Are to many inadvertences in just few words (just looking at a component you can't conclude anything till you will see its datasheet).

Regarding PCB, I am attaching another picture with drivers. Even the quality of picture is not soo good (I don't own a digital camera), you will be able to see the green color of flux (solder mask) paste over PCB. As expert, you must know what does it mean!

lasersbee said:

Be carefull that your sales pitch does not backfire in your face... members here
are loyal............

Click to expand...

Not necessary to be so carefuly ... When I started this project I didn't ask for anybody advice or support! I am taking the risk! You are reading diagonally my posts. I said that even will be no sales here, our community already have a bennefit: a driver at 6USD and the one which will produce it, will be forced to make it better and sell it under 6USD (read above)!

lasersbee said:

BTW... The only technical specification difference between the two drivers that
I could see is that your Driver goes above 400ma to at usable max 550ma...
as I tested them...

Click to expand...

The only technical spec about this driver is: 30mA up to 7-800mA/5-16V and its quality has been already demonstrated above (in worse scenario as possible)! The price is much cheaper. The components inside are better. I can go at 3USD/piece if i'll use the same components like those used to build the other driver!!!

lasersbee said:

Other than that.... they both do the same job...

Click to expand...

Shortly: is other product, same scope, extended destination/use (as has been stated at the beginning of this thread)!

I wish you good luck in the future and thanks for your time!

Regards,
Alx

the quality is pure (has been taken with my phone camera)

Hey Alx...
a few things that you seem to not understand...
First... I never agreed to let you look over my test results...
I didn't want you to bias me in any way...

I am not an employee of yours and I have no legal commitment to you...

I agreed to do a side by side review of the 2 drivers (Alx and rkcstr)... I did..
I agreed to let you know when I post it here... I did..

I believe that I'm a neutral LPF member doing a fair and unbiased review of the
two Drivers argued about in this thread...

I was not aware that we had a relationship... and I don't care if you think "it"
has ended..

To condense my Review.....

- The 2 drivers are basically the same...
- The PCB prints/traces are not the same...
- The components used on both Drivers are not identical...
- At the same output... they both dissipate about same amount of heat...
- The rkcstr driver uses a Silk Screened PCB... the ALX test PCB did not...
- The Alx Driver can deliver a higher current...
- The Alx driver is less expensive...

Now to your last post.... I'll take it in the order you wrote it...

How can you tell me that what I tested and saw with my own eyes is wrong...
What is wrong with you...

As to "same quality components" ....
Do you manufacture your Capacitors... Diodes...Resistors and Regulators....
or do you buy them like rkcstr and myself from a well known and trusted
manufacturer that adheres to top Quality Control of it's products.
If you don't manufacture them yourself... how can you say that the "Quality"
would not be the same....

"Flux Paste" is not Solder Mask.....
You did not send a Solder Masked PCB driver to me... so I have no idea what
yours looks like... and I can't see anything in your out of focus photos...

Your sales approach... to put it mildly.... SUCKS....
I would not buy from you in fear of you complaining my money is not "good quality"...
I don't care if you are selling them for $1.00..... I would not want to to deal with
you in the future...

You can argue..."30mA up to 7-800mA/5-16V".... all you want...
Maybe YOU should read my Review....and understand what I tested...


I did a fair review of the 2 drivers... and you keep arguing with the results and
yourself. In retrospect... I should have declined to do the review for you....

I hope that any others that are thinking of doing/posting a review on this Alx Driver
think twice.... your results may get argued to death by Alx himself...

You can think what you want... but you are on your own....
Good luck with your sales......................

NOTE:-
when someone does a Review of the LaserBee I... I accept it for the way it
was written and intended... whether it is good or bad... only the Reviewer knows
what he saw and experienced.
On the other hand...if I had a bad product... and someone didn't give it a 100%
review... I would probably become defensive.... Just a thought.....


Jerry

lasersbee said:

Do you manufacture your Capacitors... Diodes...Resistors and Regulators....
or do you buy them like rkcstr and myself from a well known and trusted
manufacturer that adheres to top Quality Control of it's products.
If you don't manufacture them yourself... how can you say that the "Quality"
would not be the same....

Click to expand...

each electronic component has a technical data sheet. Is not necessary to manufacture it. All manufacturers are offering data sheets! engineers are always consulting this data sheets (to see performance of each component, compare products quote prices, etc) before to build a circuit or order components! The rest, is very simple...

lasersbee said:

I don't care if you are selling them for $1.00..... I would not want to to deal with you in the future...

Click to expand...

I never expected any business from your side or to make a real business from this project. Here are already few happy customers (already received this driver) and this project is addressed for lpf members, as I said to many times above... Don't be anymore preoccupied about this project. We are in absolute consensus: will not be any future interference between you and me. Is not necessary to inform me/us about your decision. In rest, you are doing just speculations/suppositions and expressing just your feelings. I can't comment it... just I respect it!

I wish you again, good luck in your business.

Alx

Just for information, are you maybe planning a SEPIC driver, e.g. built around the LM3410, as well?

dr-ebert said:

Just for information, are you maybe planning a SEPIC driver, e.g. built around the LM3410, as well?

Click to expand...

hi dr-ebert,

I know, you are looking to a good and powerfull booster and here exist one sold at 26USD. I analized this option before to take the decission to produce the actual one... Let say that I can do a good booster at lower rates, but I have few concers/questions for you:

- any configuration/schematics has been analized, produced higher quotations than actual driver presented here at 6USD. also, higher currents are not necessary now (mostly all our diodes work under 0.5A), so we have a very short market segment here (thinking only to our lpf members)

- I saw that other peoples are organizing presales here, at higher rates (around 10USD) than 6USD which I offered actual driver (better price, better specs, already assembled and tested). And this, for something which is not stocked and have lower tehnical specs!!! Why don't buy it now, already assembled/tested, at lower rates a powerfull driver? Can you guess? I am almost sure that here is not a real market where we can discuss using standard commercial terms.

- I already have 2 projects on development (driver and 405nm lens) and actual budget exceed initial expectations (don't ask me, you don't want to know), so will be difficult to continue to sponsorhip other supplementary projects, without minimal guarantee. And all signals I have, seems to confirm above theory, and I think that nobody in the world will/can continue to sponsorhip a project without future. But who knows, maybe in the future, someone from chinese manufacturers, will produce it (of course, not especially for us) for large market, at better rates even existed before!

- let me know: how much do you think that worth to be payied for a good booster here? how many pieces/monthly? SMD or NON SMD? Do you have some predictions? If you dont know it, just post here your expectations/approximations, how would you like to be!

A booster at 2-5W could be better option for anybody (2-5W) and will unify all our needs, but I am identifying some problems:
- funds/budget available
- price/item
- quantities/order
- order is repetitive or not? if yes, how often?
- size of PCB and technology used (SMD or through hole)
- cooling (yes, no, partially)

Regards,
Alx

Alx, i think your a douchbag, you are very insecure and take things really personally and defensively, and go off on stupid tantrums. It could be the language barrier but I think I have a pretty good idea about your character. I can't believe i read this entire thread. That doesn't mean you didn't design a solid driver though. However you're new and havent been around long enough to prove youself so the only thing you have going for you is this $6 price you been throwing around. OK ill take 10 drivers shipped to me for 60-70$ no more. If you can't do it then your useless to me... And many others here.

whatsupadrian said:

However you're new and havent been around long enough to prove youself so the only thing you have going for you is this $6 price you been throwing around. OK ill take 10 drivers shipped to me for 60-70$ no more. If you can't do it then your useless to me... And many others here.

Click to expand...

Hi Adrian,

Sure I'm new, but any way begins with the first step, so your argument is not an argument. Also, don't be hurry to express something about someone you don't know. Regarding you question, I can control only the price of this driver. From my past experiece M1 (5USD - limited to 4 drivers anyway) seems to have some problems outside EU (USPS proved to be unreliable) and for this reason I decided to suspended it for customers outside EU (to protect you and me about future claims). So, as shipping method, remain only M2 (around 25USD), anywhere.

If you are still interested, just decide which quatity is profitable for you (using M2 as shipping option) and drop me a line at xella71@grad.com. Rest of details will be discussed in private.

Regards,
Alx

You're right, it's not an argument it's a FACT that you are new and have no reputation backing your product. And another FACT, USPS is VERY reliable, around here it's better then Fedex and UPS. This is a public forum and everyone here including you and I are entitled to an opinion. If you don't like it then don't participate.

Sorry, not going to pay $25 for shipping... that's more than the price of 4 drivers alone. 10 drivers weighs almost NOTHING. That's super gay! Rkcstr is shipping to me is $2.50

I can't speak for anyone else here but you lost my business. Good luck with others.

I just bought 10 rkcstr drivers with the proven reliability and great tract record and GREAT customer service. And I wasn't being forced with expensive high shipping costs... If you buy 10 you get a nice little price break, and if you preorder you get 10% and if you use LPF coupon you get ANOTHER 10% off.

Perhaps if you choose to reevaluate your shipping options i may consider your drivers in my next batch(probably in 2-3 weeks). If you are serious here that is...

Dear Adrian,

Sorry to see you so bumpy ... see my answers inline.

whatsupadrian said:

You're right, it's not an argument it's a FACT that you are new and have no reputation backing your product.

Click to expand...

This driver has clear technical specs/functionallity and you are interested about it ... my membership (newer or older) has nothing to do with it. as i said, any way start with first step ...

whatsupadrian said:

And another FACT, USPS is VERY reliable, around here it's better then Fedex and UPS.

Click to expand...

You are a little bit absent: I am talking about USPS International. I'm not from USA.

whatsupadrian said:

Sorry, not going to pay $25 for shipping... that's more than the price of 4 drivers alone. 10 drivers weighs almost NOTHING. That's super gay! Rkcstr is shipping to me is $2.50

Click to expand...

again, you did not read my first post/update. there you will find all details about shipping and proposed price/schema. I can agree with you, that M2 perhaps not worth if you want to buy just few drivers (stated above, very clear too).

whatsupadrian said:

I can't speak for anyone else here but you lost my business. Good luck with others.

Click to expand...

Is other product, better range/specs/componets inside. I cannot understand your frustration. I presented above, what can I do. Just buy more drivers, and I can cover the shipping cost (I told you to contact me in private to arrange details...).

whatsupadrian said:

I just bought 10 rkcstr drivers with the proven reliability and great tract record and GREAT customer service. And I wasn't being forced with expensive high shipping costs... If you buy 10 you get a nice little price break, and if you preorder you get 10% and if you use LPF coupon you get ANOTHER 10% off.

Click to expand...

The driver you bought is over 10USD plus shipping, poor specs/functionality than this one.

whatsupadrian said:

Perhaps if you choose to reevaluate your shipping options i may consider your drivers in my next batch(probably in 2-3 weeks). If you are serious here that is...

Click to expand...

unfortunattely, does not exist other way for USA. these are carrier rates. even i want, i can't change their rates, i'm not owning this service ...

Regards,
Alx

You fail to understand that reputation plays a critical role here. I know because I'm new myself. Too many members get burned and scammed by new members here peddling their wares, that the very small additional cost of rkcstr's drivers are worth the piece of mind. The difference between you and me is I have a group of members here who know im serious here, you on the other hand have been burning bridges since you joined. I know by making you that offer I was taking a risk. And being that I was already taking a risk i choose to further my risk by asking for a cheaper alternative shipping, of which all 10 drivers would weigh less than a pound! And as far as being better components/parts making your driver superior, well good for you and your opinions. Shame the rkcstr does EXACTLY what its supposed to and does it flawlessly and has a reputation behind it for being a solid driver. It satisfy our needs, and you build a clone with a different selection of parts. Your comments are very biased, you throw out rkcstr's full price driver and put your quantity discount price for comparison. You need to get your facts straight, because i just paid LESS than $10 a driver and the shipping turned out to be $3 for ALL 10 drivers. Also the rkcstrs are now manufactured in the US, and we sure do like to keep our money in our economy. I'm done with you, you will just argue with ever line I write, and everyone else for that matter. Besides, most people like you are hiding skeletons in their closet. If you want my business then you will provide a solution for the expensive shipping issue at quantities of 10-20units. Good luck to you, to put it bluntly, your marketing scheme is a FAIL. I wont reply here any more, If you want my business(someone does) then you will honor the offer I have already made in PM.

@ alx...

It just goes beyond reason that you continually BASH the rkstr driver...:tsk:

The driver you bought is over 10USD plus shipping, poor specs/functionality on a single unit quantity costs

Click to expand...

You haven't said one nice word about the rkcstr driver since you've been
on the Forum...

The rkcstr Micro-Drive is a Hiqh Quality Current Regulated Laser Diode driver
that was designed to output up to 400mA... and that's what it does...
and the Members here are very happy with it..

The Micro-Drive is assembled with a professionally produced Silk Screened
PCB using High Quality new prime stock electronic components...

We already know that your driver outputs more current than the rkcstr
driver... but that is the only difference in specifications..

As to the pricing....lets have a look at that...

Keeping in mind that the LPF community is not a business but a hobby..
Members can't buy 100 drivers just to build 1 ot 2 Lasers...
So lets say they would buy betwen 1 and 10 drivers at a time...

Micro-Drive ------------ alx Driver

1pc = $ 10.53 ----------- 1pc = $ 10.00
S/H = $ 02.50 ----------- S/H = $ 25.00
Total $ 13.03 ----------- Total $ 35.00


10pc = $105.30 --------- 10pc = $100.00
*S/H = $002.50 --------- *S/H = $025.00
Total = $107.50 --------- Total = 125.00

per 10pc $10.75ea ------ per 10pc 12.50ea

Your drivers are still more expensive than the rkcstr Micro-Drive for the
quantity of drivers an average LPF member would need...

If you want to sell them by the hundreds... then I think you are in the
wrong place..


Jerry