Digital Pot setup

[CDRIVE]

Hi Chris

I have tried to create the Gerber file myself but have found out that the free version of Tina does not allow you to do this. I have had a look at the Tina site and can see that the Tina design suite basic edition allows you to create Gerber files.

https://www.designsoft.biz/orders/order.php

I thought I would just ask, if you thought this would be a worthwhile purchase for me and is it easy to learn and use?

Regards

Justin

Justin, many posters are drive by's that I'd never recommend spending the cash for a good spice simulator. You're not one of them. You have a keen interest in electronics and I don't think that your motor controller or the LED head light is going to be your last project. So, yes I think it's a good investment for a guy like you.

Btw, I've never used the PCB Creator in Tina so if I did it for you I'd have to learn how to use it myself.

Chris

 

[JPU]

Hi Chris

Thanks for that.. I have just had another look at the Tina site and was just about to buy when I remembered I had cut and copied an image of the Picaxe chip from the JPEG of the schematic that you created. I had a thought then, "this will not work if I try to use the "create PCB" module"! as the image of the Picaxe will not make sense to the Tina s/ware.

So my question,(as I have had a look at the component lists but can not find it), is how did you create the picaxe 08m2 in your schematic? Did you find it somewhere or did you create it?

Regards

Justin

 

[CDRIVE]

Hi Justin,
Yes, you're absolutely correct. See, I knew I was right about you. You're an excellent student... like a dry sponge! This discussion is not about you...
https://www.electronicspoint.com/newbies-secret-circuits-circus-t250431.html

Anyway, the Picaxe models were created by me but since I never had any intention of creating a PCB there is no 'Footprint' association for them. They are also empty shells and can't be simulated.

Here's the good news.. If you recall all Picaxe chips cross reference to a Microchip PIC model. The Picaxe MCU library should have the equivalent PIC chip that you can replace my blank model with.

Chris

 

[CDRIVE]

I took a look see in the MCU library. It would appear that the PIC12F629, which is the older Picaxe 08 has the identical footprint of the 08M2. On that note, I would love to know what the hell the symbol designers were thinking when they made it so damn big!

 

[JPU]

Help, help....Anyone please

I have sent one of these boards out. I have been testing the board my self for ages as a hand soldered prototype. The unit has worked well. The only difference between the protoboard and the board I have had made is that the manufactured board also has a TS7815, to step the V down from 29V to 15V for the LM7805....

However, the first commercial version of the machine that I have made and sent to a friend for him to use has come back after 5hrs use. The fault is the TS7815 Regulator has blown. This was the only thing that I have not tested!!!! I am gutted as the friend is also a potential buyer and I need some money back........

I am not sure what to do here,,,,out of my depth,,again.

The TS7815 says its rated to 35V absolute maximum so why has it blown???


What can I do to quickly fix this problem...I dont want to send it back with just the LM7805, even though it works in mine, as there is a slight glitch, when the battery is fully charged the motor stop/starts for a minute or so and then settles. The TS7815 had solved this.....

Is there a better way for me to do this..eg should I use a bigger regulator for the first steup down.. The battery is 21V-29.1V


Help please, as I need to get this in the post for Monday.....

Thanks

JPU

 

[CDRIVE]

Justin, I have an important appointment with a beer tap, so I gotta go. If it's an input spike that's killing it you may be able to use a small resistor and 27V Zener on the input. I'll look at it longer when I get back and have a MUCH clearer head.

In the interim there's many good minds here that probably don't have an appointment.

Chris

 

[JPU]

Justin, I have an important appointment with a beer tap, so I gotta go. If it's an input spike that's killing it you may be able to use a small resistor and 27V Zener on the input. I'll look at it longer when I get back and have a MUCH clearer head.

In the interim there's many good minds here that probably don't have an appointment.

Chris

Brilliant, Thanks Chris..

Enjoy at the watering hole.

JPU

 

[gorgon]

what sort of supply currents are we talking about here?

TOK

 

[JPU]

what sort of supply currents are we talking about here?

TOK

Hi Gorgon

This is a good question, I am sure, but what do you mean.

Its a Lifepo4 battery. The unit is a step up/down controller. It runs 3 LEDS connected to the buttons. It has a kia358 and a picaxe 08m2..

I'm a nube and I'm not sure what you mean..


I do know that the battery can supply 8Amp/hr if needed but is that what you need to know?


Thanks

JPU

 

[gorgon]

I was thinking about the power loss in the 7815, due to the current drawn in your circuit. From what you say, it should not be many mA. The 7815 tolerate around 2W with no extra cooling. That should be around 133 mA with a 30V supply.

I'll think that spikes from the motor on the powerlines can cause your problem.
If you put a 5V zener in series with the battery input an a 30V zener over the Vin in the 7815, you should be good. this will clamp the input voltage reduced with 5V to max 30V. This will also reduce the thermal stress, if any, ond the 7815.

I would also add a 2uF2 or 4uF7 to the C3 position. 100nF could be on the low side and you may get oscillations between the regulators. keep the 100nF and add an additional capacitor. The same goes for the 5V regulator, add a similar capacitor to the C4.

TOK

 

[CDRIVE]

Justin, is your circuit connected while the battery is being charged? Did you ask your friend if it failed while he was using it or after a charging? What's the battery voltage at full charge and max voltage while being charged. At times like this we have to explore all possibilities.

Chris

 

[JPU]

Hi Chris

He hadn't charged the battery yet. I have included a switch in the design that isolates the motor circuitry when charging any way.

The battery fully charged is about 29.1V



Justin

 

[JPU]

If you put a 5V zener in series with the battery input an a 30V zener over the Vin in

TOK

Hi Gorgon

Can you explain this in layman terms as I am a nube, What do you mean by "30V zener over the Vin" or if anyone else can explain Id appreciate it. I have to get this fixed today for posting tomorrow....

Thanks

Justin

 

[JPU]

I would also add a 2uF2 or 4uF7 to the C3 position. 100nF could be on the low side and you may get oscillations between the regulators. keep the 100nF and add an additional capacitor. The same goes for the 5V regulator, add a similar capacitor to the C4.

TOK

Hi Gorgon

I have a box of capacitors I am not sure what a 2uf2 or 4uf2 is

I have a 2.2uf/50V and 4.7uf/50V are these suitable?

Also please take a look at this site

http://www.maplin.co.uk/1.3w-zener-diodes-19090

The zener diodes are QF46A AND QF64U ,,will these be suitable for the fix....


Thanks

JPU

 

[CDRIVE]

Justin, I want you to know that I was going to tell you that you made a rash decision and a common nube mistake. That being... having a production board made without first having a few field tests built on a universal project board. Unfortunately for me (embarrassing too) it's not your fault. When you told me that you were having the board commercially made I should have stopped you dead in your tracks!!!!

Justin, at this point, myself and anyone else that responded to this problem can only guess what popped the TS7815.

(1) Input too close the the 35V Input Max?
(2) Spikes snaking back from the motor or controller?
(3) TS7815 oscillation?

We really don't know at this point.

Attached is a schematic that hopefully will address all three possibilities. Z1 can be just about any 5V-1W Zener.

One last note and once again ... my fault! It's always good practice to place decoupling caps (also called "bypass" caps) on the Vdd or Vcc of each chip on a board. They should be mounted as close to chip's pin as possible. Decoupling caps can be anything from 1000pF to .1uF. Any value in this range is better than nothing. I know I included them in my schematics but when you posted your Gerber ready schematic I should have caught that they were missing.

Well, I thought that was my last note but here's another. Your first runs of this controller should have been considered Beta models and such conveyed to the customer. They should have been given to good customers as a gift or buy on trial basis. Thankfully, I take no responsibility for this.

Best of luck,
Chris

 

[JPU]

Hi Chris

I have just got in. I am very grateful. Ill send a more detailed post later. I am going to get building this instantly.

However, I only have the IN4007 diodes you advised me to get for the other project. I have been out and bought the zeners but I do not have a IN4001 and the store is now closed..

Is the IN4007 ok to use in place of the IN4001

I have just found a P6 IN4003???

Justin

 

[CDRIVE]

Hi Chris

I have just got in. I am very grateful. Ill send a more detailed post later. I am going to get building this instantly.

However, I only have the IN4007 diodes you advised me to get for the other project. I have been out and bought the zeners but I do not have a IN4001 and the store is now closed..

Is the IN4007 ok to use in place of the IN4001

I have just found a P6 IN4003???

Justin

Any of the 1N400x series will work in this application but I'd use the 1N4003.

Chris

 

[JPU]

HI Chris

Ok, that's better. I have been pulling my hair out all day and got back to see your email. I was so relieved, thank you.

I was going to attempt Gorgons idea but he doesn't know me as well as you! I am a kind of a no schematic, no idea, kind of guy. (that's me, who has the no idea)

Your schematic confirmed which way around the diodes and zener should go!

I have built the additional circuit and its in. It seams to work. I put a meter across the output of the new (additional) circuit and it gives a 5V drop. The input from the battery was 26.1V and the meter read 21V I assume that's the zener.

I am not sure how all that circuitry helps, I would really like to know more but reading on the internet just gets confusing without being able to ask questions as I read.

As for testing the circuit,I have been, for 2 months. The only thing missing was the 7815. I know my proto board didn't have that reg, as you pointed out I was running the 7805 to the max. When I had the boards made up, I had help with the Gerber files from a local chap and he made the slight alterations with regard to the caps.

I have sold this unit with a months pre-purchase trial to a friend. He knows the situation and is getting the machine 50% of what the final price will be. However, I told him that all the testing had been done and I was confident in this version.

As for the machine.....he said for the time it worked,,,,it was the best he has ever used. He has owned virtually all the current commercial versions and in his words, this model is light years ahead!!!

I was hoping to put a few pics together with a video of it in action to bring the thread to a nice conclusion. More testing required!!!! I think.

Anyway,,,I will keep you posted on this patch,, and thanks again. I wish you were closer as I would buy you a few of those pints you enjoy and I, enjoy!!

Also, thanks Gorgon for your help also, I appreciate it!

Cheers

JPU

 

[CDRIVE]

Keep us posted,

Chris

 

[JPU]

HI Chris

So far so good!

I have tried to research how the fix works but I am not getting it! Could you explain to me how the Zener works like this and what the 1N002 diode is for. Its the Zener that I am most confused with..

I have to be honnest, I read this ("A Zener is not like a normal diode. A normal diode lets current flow in only one direction and needs to be installed in the correct direction. A Zener diode is placed in the opposite direction, against the flow of current. A Zener diode will prevent current from flowing until it reaches a certain voltage, depending on the diode rating. Once this critical value is reached, current is allowed to flow. The diode will also try to keep the outgoing voltage at its rated level, say 5 volts. If you feed 10 volts through the diode, the voltage might climb to 5.5-6 volts, but it will try to stay at the same voltage. If you feed too high a voltage through the diode, it will break down and fail.")

and its making me panic!

Regards

Justin