Output interface to 24 volts

[dj_trippn]

Hi I have searched the forum but cannot find a solution to a reasonable simple question.

I am interfacing my 18X picaxe to a motor drive. I have 8 outputs from the axe to the drive and 4 inputs from the drive. My problem is the I/O to the drive is 24 volts. The drive inputs are transistors so only draw a few tens of millamps.

What is the best driver to interface these devices? I have only ever used FETs which I could do but I was hopping to find a package that included say 8 FETs/relays in one simple package and to shrink down the size of the circuit. Similar to this chip SY4090 from jaycar.co.nz, but more on one package. http://jaycar.co.nz/productView.asp?ID=SY4090&CATID=&keywords=relay&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

Any ideas, the simplier (and less components) the better. As always.

Thanks for your help in advance.

 

[leftyretro]

Hi I have searched the forum but cannot find a solution to a reasonable simple question.

I am interfacing my 18X picaxe to a motor drive. I have 8 outputs from the axe to the drive and 4 inputs from the drive. My problem is the I/O to the drive is 24 volts. The drive inputs are transistors so only draw a few tens of millamps.

What is the best driver to interface these devices? I have only ever used FETs which I could do but I was hopping to find a package that included say 8 FETs/relays in one simple package and to shrink down the size of the circuit. Similar to this chip SY4090 from jaycar.co.nz, but more on one package. http://jaycar.co.nz/productView.asp?ID=SY4090&CATID=&keywords=relay&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

Any ideas, the simplier (and less components) the better. As always.

Thanks for your help in advance.

well it would sure be useful to see the actual input and output circuits for the motor driver package to figure out the easiest and cheapest method. Got a link to a data sheet?

Lefty

 

[dj_trippn]

Hi Lefty,

sorry I didnt provide this information because I thought it was irrelevant. I found a datasheet on the net for a similar drive, which has the same IO on it. http://www.inverters.ru/dynamic/managers/manage_9/files/I527-E2-02_3G3MV_Users_Manual.pdf

Page 2-18 shows the drive input internal circuit, Page 2-20 shows an overall diagram. S1 - S7 are the drive inputs and P1 - P2 are the drive outputs on this drive.

 

[westaust55]

Have a look at the ULN2803A octal Darlington transistor driver as used on some PICAXE starter boards. these can handle "OUTPUT VOLTAGE TO 50 V"

Use the inverter NPN input settig and connect the ULN2803 and inverter ground terminals (SC on inverter) together.


available from Dick Smith Electronics
uln2803A 8-Way Darl 5V TTL Inp Static Sensitive 18-Pin DIP Z6282

Altronics P/No: Z3010
http://www.altronics.com.au/index.asp?area=item&id=Z3010


or MicroZed
http://www.microzed.com.au/chips.html

 

[dj_trippn]

Thanks Westaust55, that looks like it will do the trick so thanks. I'll give that a go this weekend and hopefully I should have the motor moving.

Do you know of any devices with multiple relays in them?

Thanks

 

[westaust55]

Thanks Westaust55, that looks like it will do the trick so thanks. I'll give that a go this weekend and hopefully I should have the motor moving.

Do you know of any devices with multiple relays in them?

Thanks

Sorry, not aware of any devices or "building block" that have multiple relays in a single package.

 

[westaust55]

relay boards for PICAXE interface

Came across these today while surfing for other information:

Did find this board by PH Anderson which acts as an interface for 4 signals. US$49.95
A good board but think it is overkill for what you are trying to achieve.
http://www.phanderson.com/serial_relay.html

This simpler board comes in an option with 4 relays and 5Vdc coils. US$45ea not much saving for only US$5 less.
http://www.winfordeng.com/products/rlp104.php

I am sure if you do some specific searching for yourself you may find something better/cheaper.

 

[dj_trippn]

Hi I have purchased the ULN2003A, did not have 2803A available. I have got it working great thanks. I will be able to use it for the outputs from the drive to the picaxe too?

Do I need to connect pin 9 "free wheeling diode" to anything? What does this pin do? (pull up pin when output off?)

 

[westaust55]

The free wheeling diodes are for cases there is inductors such as motors. When using the Darlington transistors to drive the VSD inputs, there is no need to connect.

But if you (later) use the Darlington array to drive/control relays or motors directly, then connect that pin to the +V supply going into the motors.

Purpose of a free wheeling diode (in simple terms):
When an inductor is disconnected, the voltage flips polarity and can result in very high voltages across switching components. The diode provides a path for the current to flow and dissipate the energy and thereby protectes the switching devices from over-voltage conditions.