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Posts posted by HarryA

  1. Making your R1 2000 ohms from 1000 ohms improves the output with slightly  less output power. What do you expect for output power and what do you have for input voltage?

    Also the transistors are large current perhaps some thing smaller? The circuit you are using has a base current of about 1.8 ma for the 2SC5200 at 150 mv peak input that is quite low.



  2. The output looks good in the simulator at 120mv(peak to peak) the current through the 8 ohm resistor is about 500ma pp which is about 1 watt. At 150mv the output is starting to clip on the bottom. This is do to the PNP Q3 having more base current than Q2. Q3 is directly connected to Q1 while Q2 is off from Q1 by the two diodes or 2 * 0.7 volts  I would think. The base currents; green is Q3 and yellow is Q2.


    I like this  circuit better as it is symmetrical; both transistor get the same amount of base current I would think.


  3. So you have a double pole single throw switch. There are two sets of contacts in the switch. Two of the connectors connects to one set of contacts and the other pair of connectors connect to the other set of contacts. You need to know which pair of connectors connects to each set of contacts. I believe.



  4. Using what I could find for similar transistors in the simulator I used your  circuit:


    Green trace is the current through the NPN and yellow the PNP. The current through the 8 ohm load looks good inspite of the asymmetry in the transistor currents.



    Connecting the PNP  between the two diodes removes the asymmetry but changes the output current:


  5. On 7/6/2021 at 5:21 PM, Engr. Philip said:

    Which site can I buy good quality electronic components at cheap price and with free shipping

    Good quality and cheap price do not go together.  I buy cheap from Ebay but not always good. I buy some from Amazon.com because I have prime and can get things quickly. Jameco.com is a good hobbies supplier but they are on the west coast and I am on the east so delivery is slow; also  digikey.com is high quality but to slow for me.

  6. You do not give enough information to enable one to be very helpful to you. What are your requirements for you off road rover? You may look at similar devices (like electric scooters perhaps) via the internet and see what size motors they use. 

    Here are some 12 volt motors from 1hp to 1/3 hp. https://www.ebay.com/itm/233312841977?_ if that link does not work search on ebay for "DC MOTOR, 1/3~3HP, 56C, 12/24/90/180V, 1750RPM, TEFC, Permanent Magnet"

  7. On 6/9/2021 at 10:47 AM, torpid whale said:


    My batter is this one. and I have the correct PD charger. and my boost converter is capable of supporting the needed current.

    Can you provide a block diagram of your set up? You speak of "my boost converter" isn't the ZY12PDN a type of boost converter? From the USB_C five volts to various voltages?

    Some useful data here: https://www.alexwhittemore.com/notes-on-usb-pd-triggers-and-zy12pdn-instructions/

  8. Yes, I think you are correct. Scherz and Monk's Practical Electronics for Inventors has: metallized ployester film capacitors: 2u2 = 2.2uf. The K would be -/+10%.
    also: "In case, small values with decimal points needs to be represented, then the alphabetical letter “R” is used such as 0.5 is represented as 0R5, 1.0 as 1R0, and 2.2 as 2R2 respectively."

    You can find 1.5uf 250vac capacitors on Ebay that ship world wide. It's difficult to tell one where to purchase something if you do not know where in the world they are.

    How do you fix a horrible URL?

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